43
the technical manual 4 OCCUPATIONAL INTEREST PROFILE Measures of Personality Values & Interests
thetechnicalmanual 4
OCCUPATIONALINTERESTPROFILE
Measures of Personality Values & Interests
ONTENTS1 OVERVIEW
2 THE PSYCHOMETRIC PROPERTIES OF THE OIP
3 ADMINISTRATION INSTRUCTIONS
4 REFERENCES
c
2
31 STANDARDISATION SAMPLE COMPOSITION
2 OIP INTERNAL CONSISTENCIES & ITEM TOTAL CORRELATIONS (ITC’S)3 CORRELATIONS BETWEEN OIP PERSONAL WORK NEEDS (N = 2556)4 CORRELATIONS BETWEEN OIP VOCATIONAL INTERESTS (N = 2556)5 CORRELATIONS BETWEEN OIP INTERESTS & WORK NEEDS (N = 2556)6 CORRELATIONS BETWEEN 15FQ AND OIP WORK NEEDS (N=1971)7 CORRELATIONS BETWEEN 15FQ AND OIP VOCATIONAL INTERESTS
8 CORRELATIONS BETWEEN JTI AND OIP (N=1971)9 CORRELATIONS BETWEEN OIP SCALES AND HOLLAND’S VPI INTEREST SCALES
10 CORRELATIONS BETWEEN OIP AND VPI ADDITIONAL SCALES
11 CORRELATIONS BETWEEN OIP INTERESTS & ROTHWELL-MILLER
12 CORRELATIONS BETWEEN OIP AND OPP SCALES
13 CORRELATIONS BETWEEN OIP WORK NEEDS & 16PF
14 OIP (N=2556) FACTOR PATTERN LOADINGS
LIST OF FIGURES1 OIP PROFILE FOR PERSUASIVE OCCUPATIONS
2 OIP PROFILE FOR PRACTICAL ROLES
3 OIP PROFILE OF BUREAUCRATIC ROLES
4 OIP PROFILE OF CARING ROLES
LIST OF TABLES
4
1OVERVIEW The OIP is a test developed for useacross a wide range of assessmentand guidance situations. The test
was developed in the UnitedKingdom on a large sample of indi-viduals drawn from a wide range ofoccupational groups. Thus the OIPis particularly appropriate for usein assessment and Guidance in the
UK. The OIP contains twelve scales,five measuring personal qualities
and seven measuring occupationalinterests. Each of the twelve dimen-
sions measured by the OIP is bi-polar. That is to say high or low
scores on each dimension measureopposite characteristics (e.g. extra-
version v introversion, tough-minded v tender-minded etc.). The
characteristics which are measuredby the OIP have been selected for
two reasons. Firstly, for their rele-vance to assessment and guidance
decisions, and secondly, because ofextensive research evidence demon-strating their validity. Thus the testuser can be confident that the OIPis measuring meaningful aspects of
the candidate’s personality.
1 MEASURING PERSONAL QUALITIES
2 THE DEVELOPMENT OF THE OIP
3 THE OIP INTEREST SCALES
4 THE OIP WORK INTERESTS
6MEASURING PERSONALQUALITIESInterest in the measurement of psy-chological characteristics (psycho-metrics) can be traced back to thelate 19th Century (e.g. Galton,1884). Pioneering work in the fieldof vocational interest measurementwas carried out by E.K. Strong, Jr.,on the Strong Vocational InterestBlank in the 1920’s. But it was theimpetus provided by the secondworld war which resulted in suchinterest developing into a serious sci-entific enterprise. During the warthere was a great need to select mili-tary personnel for air crew trainingwhich led to the development of anumber of psychometric tests bothhere and in the United States. Themain interest at this time was in thedevelopment of IQ tests, or tests ofmental ability as they used to becalled, rather than in the develop-ment of personality tests. While thepsychological theory, trait theory,which underlies much of personalitytesting had been developed byAllport in the 1930’s it was sometime before this was used in anattempt to construct personalitymeasures. It was not until after theSecond World War that such workcame to fruition.
The reasons for psychologicaltesting burgeoning after the warwere basically twofold. Firstly,modern computers permitted thelengthy and complex statisticalanalysis of data which is required to
produce a test. Thus DavidCampbell (Campbell, 1974) wasable to use the computing powernewly available to carry out theresearch and analysis which led tothe Strong-Campbell InterestInventory in a relatively short periodof time. The second reason for thedramatic increase in psychologicaltesting probably lay in the growingrealisation that only by being able tounderstand and measure humanbehaviour could we hope to predictthat behaviour with any degree ofreliability.
The principles which underliepersonal qualities and interest mea-surement are not as complex as theymight first appear. A questionnaire issimply a collection of questions, or“items”, which assess an individual’sinterests or characteristic ways ofthinking, feeling and acting in differ-ent situations. Items do not have todirectly ask a person how they typi-cally behave (e.g. I am a warm,friendly person). All that is neededfor an item to work is for people torespond to it in a consistent way.Thus good questionnaires can bereliable, yet contain items which arenot transparent or obvious in whatthey seek to ascertain. In the area ofoccupational guidance and assess-ment it is in fact best not to usetransparent items, thus making itharder to fake test results. Of coursethere is less reason for individuals
7who are completing questionnairesfor career direction or developmentpurposes to wish to portray a falselypositive image than there is for anapplicant for a job.
Personal qualities and interestquestionnaires take items whichmeasure different aspects of the samepersonality characteristic or interestarea and combine them to form sub-scales or dimensions. By askingquestions which address many dif-ferent facets of a persons life, ques-tionnaires attempt to get a broadpicture of an individuals interestsand how they usually act in differentsettings and with different people(e.g. with friends, at work, at formalsocial engagements etc.). Thus whenwe say a person is extroverted wemean that he is sociable, lively, out-going and friendly: that he usuallyseeks variety, change and excitementand has a great need for others’ com-pany. In addition to addressing thosecharacteristics which are extreme oroutstanding questionnaires alsoassess those ways in which a personis average.
In personal development situa-tions we are often as interested tofind that a person is average on acertain trait as we are to identifytheir most notable or extreme char-acteristics. For example having an
average score on a particular trait,say assertiveness, may better fit thedemands of the job being consideredthan being either highly change ori-ented or very accommodating.Average scores can describe a bal-anced and flexible position, wherethe person is capable of displayingthe strengths which are found atboth of the extreme ends of the per-sonality dimension. In the case of aperson who has average levels ofassertion for example, they are likelyto strive to achieve a balancebetween being task focused andachieving results yet being sensitiveto others’ needs and avoiding inter-personal conflicts.
8An initial theoretical structure forthe interest test was developed froma review of existing vocational inter-est questionnaires (e.g. KuderPreference Record, Rothwell-MillerBlank, Vocational PreferenceInventory etc.). Also of importancein the development process was thepioneering research carried out byJohn Holland in the area of generalcareer themes. Holland (1985)reporting on the culmination ofmany years research suggested thatthe main dimensions underlyingmost interest inventories could beaccounted for by means of six gener-al career themes –Realistic,Investigative, Artistic, Social,Enterprising and Conventional.
The Holland career themes arestrongly reflected in the seven inter-est scales contained in theOccupational Interest Profile. Theinitial research on the OIP suggestedthat some changes to the basicHolland scheme was desirable. Twoof the most important of these weredictated by changing circumstancessince the themes were originally pro-posed. It was decided that the enor-mous growth in the areas ofInformation Technology andComputing required the splitting ofthe Investigative theme into two
components –Scientific and Logical.It was also decided that due to thegrowing importance of the financialservices sector that the Conventionaltheme in Holland’s scheme neededwidening to include interests in bothadministrative and financial matters.
In addition to vocational interestsan individual’s personality clearlyhas a role in career choice. A reviewof the relevant literature indicatedthat five personality variables playeda significant role in career choice.Measures of extraversion, emotionalstability and conscientiousness wereincluded in the OIP as research hasdemonstrated that these three per-sonality factors account for much ofthe variance in the majority of per-sonality questionnaires. In addition,measures of the need to take controlof situations and the need for varietyand change were included because oftheir clear relevance to career choice.
Thus, a total of twelve scales,seven interest & five personal quali-ties, are measured in a questionnaireconsisting of 122 items. Personalqualities and career interest ques-tions are presented as a single test.The response format is a 5 pointLikert scale ranging from StronglyDisagree to Strongly Agree.
THE DEVELOPMENT OFTHE OIP
9If the aptitude approach to careerguidance is followed individuals aregiven a number of tests in whichthey have to perform at their maxi-mum. Their scores on the tests,which typically include reasoning,mechanical aptitude, spatial reason-ing and a range of other aptitudes,are then compared to scores obtainedby specific occupational groups.Thus, if an individual performedwell on a test of spatial reasoningthen, depending upon other criteriabeing satisfactory, a number ofcareers that involved a large compo-nent of spatial reasoning would besuggested.
The other approach to careerguidance is to offer career interest,personal qualities and, optionally,some brief form of reasoning assess-ment to provide the careers adviserwith objective and reliable informa-tion concerning their client. Themajor difference between the twoapproaches is that in theinterests/personal values approachthe client is asked questions to elicitinformation concerning themselves,while in the aptitude approach theyare ‘tested’ for their maximum levelof performance on a range of workrelated aptitudes.
Of course, the two approaches arenot mutually exclusive and it wouldoften be beneficial to combine theOIP with either a general reasoningtest such as the GRT2 or a test oftechnical aptitudes such as theTechnical Test Battery.
bk THE OIP INTEREST SCALES PERSUASIVE
Interest in persuasive roles, involvingthe communication of informationand ideas in a convincing manner.An interest in this area indicatessomeone who would enjoy speakingin public, relishing the opportunityto convert a group of people to theirway of thinking. Typical vocationalroles for those with high persuasiveinterests would be sales representa-tives, public relations and politics.
SCIENTIFIC
This scale deals with an interest inscientific pursuits including Physics,Chemistry, Medicine and laboratorywork. Such an interest indicates apreference for discovering new factsand problem-solving. Primarily con-cerned with analytical skill and scien-tific curiosity individuals with anhigh score on this scale prefer to workwith ideas and scientific principles.
PRACTICAL
This scale deals with an interest inpractical, mechanical activities.People scoring highly on this scalewould typically be interested inworking with their hands, findinggreat satisfaction in being able toconstruct something. Vocational rolesinvolving such things as engineering,machine tools, crafts, mechanicaland civil engineering would all be ofinterest to the high scorer on thisscale.
ADMINISTRATIVE
This scale is concerned with prefer-ences for organising and maintaininginformation. Both financial and cler-ical/administration areas are sam-pled by this scale. High scorerswould typically be interested in suchactivities as bookkeeping, stock con-trol etc. Other things being equal onewould expect people who display thispreference to be excellent at jobswhich required attention to largeamounts of paperwork and the keep-ing of detailed records.
NURTURING
High scorers on this scale are inter-ested in helping and caring forothers. Such individuals will find iteasy to talk to others and empathisewith them. Thus they will be good athelping people who have problems,and will probably be sought out byothers wishing to tell them theirproblems. High carers would proba-bly prefer working in helping profes-sions such as teaching, social work,health care etc.
ARTISTIC
This scale deals with all areas con-cerned with the creation of artisticproducts or ideas. High scorers willbe interested in a wide range of artis-tic endeavours such as painting, the-atre, photograph, design of all typesetc. Such individuals will tend toexpress themselves through theirartistic activities. High scorers onartistic would enjoy working in mostareas of the arts and entertainmentindustry.
LOGICAL
High scorers on this scale show aninterest in logical, rational pursuits.Such individuals enjoy solving puz-zles of all types and would beextremely interested in any activitiesdealing with logic, computation andmathematics. Of special interest tohigh scorers would be any areaswhich involved them using comput-ers for a major part of their time.
blNEED FOR VARIETY
This scale provides a measure of theextent to which an individualrequires variety and change in theirlife. High scorers will always be seek-ing new and exciting activities andwill probably become extremelybored if asked to perform the sametask for any length of time. Suchindividuals also enjoy taking risksand require some element of adven-ture or excitement in their life. Lowscorers, on the other hand, willprefer set routines and the familiarityof doing things they have donebefore. These will be cautious, safetyconscious individuals who have noneed for excitement and thrills intheir life.
NEED FOR STABILITY
High scorers on this dimension areemotionally stable, calm and com-posed individuals. Generally opti-mistic, they will rarely brood overpast failures but will instead get onwith the next task. Accepting criti-cism in a good natured way they willrarely be upset by the thoughtlesscomments others might make. Lowscorers tend to be emotionally volatileprone to sudden swings in theirmood. Easily upset by others theymay react adversely to criticism evenif this is justified. Such individualswill have a tendency to worry aboutpast failures and feel depressed attheir perceived inadequacies.
NEED FOR STRUCTURE
A high score on this scale suggests anindividual who will pay attention todetail, displaying perseverance andself-control. Well organised, they willbe careful to plan ahead, attemptingto account for any possible contin-gencies. If they start a task they willfeel compelled to see it through tocompletion. Low scorers will not bethe most organised people in theworld, tending to be careless andimpractical. Spontaneous people,they will see little need for makingplans, and will often start tasks butlose interest in them before they arefinished.
NEED FOR PEOPLE
A measure of sociability, giving anindication of an individual’s desire towork with people, be an active groupparticipant and need group supportand recognition. High scorers willdislike being on their own, preferringto be a member of a group. They willhave a great liking for social occa-sions and will not shirk from beingthe centre of attention. Low scorerswill much prefer to work alone,tending to prefer their own companyto that of others. They will have littleneed for group support and socialrecognition feeling comfortable whenmaking their own decisions.
NEED FOR CONTROL
This scale gives a measure of aperson’s preference for leading anddirecting people, taking charge andresponsibility for others. High scor-ers will be assertive individuals whoare in their element in positions ofpower and responsibility. Thriving ina position of leadership and authori-ty they love to organise other people.Such individuals will tend to take thelead in group discussions pushingtheir own views and ideas forward,paying little attention to those ofothers. Low scorers will not particu-larly like being in positions ofauthority finding it difficult to giveorders to people. They will muchprefer to be left to get on with theirown work rather than being respon-sible for organising the work ofothers.
THE OIP WORK INTERESTS
bm
2THE PSYCHOMETRICPROPERTIES OFTHE OIPThis chapter will present details con-
cerning the psychometric propertiesof the Occupational Interest Profile.
The aim will be to show that the OIPfulfils various technical requirements,in the areas of standardisation, relia-
bility and validity, which ensure thepsychometric soundness of the test.
1 INTRODUCTION
2 STANDARDISATION PROCEDURES AND
NORMATIVE DATA
3 RELIABILITY OF THE OIP
4 CONSTRUCT VALIDITY
5 FACTOR STRUCTURE OF THE OIP
bo INTRODUCTIONSTANDARDISATION : NORMATIVE
Normative data allows us to comparean individual’s score on a standard-ised scale against the typical scoreobtained from a clearly identifiable,homogeneous group of people
In order to provide meaningfulinterpretations, the OIP was stan-dardised against a number of rele-vant groups. The constituentsamples which make up the OIPnorm base are fully described in sec-tion 4.2.
Standardisation ensures that themeasurements obtained from a testcan be meaningfully interpreted inthe context of a relevant distributionof scores. Another important techni-cal requirement for a psychometri-cally sound test is that themeasurements obtained from thattest should be reliable.
RELIABILITY
The property of a measurementwhich assesses the extent to whichvariation in measurement is due totrue differences between people onthe trait being measured or to mea-surement error.
Reliability is generally assessedusing two specific measures, onerelated to the stability of scale scoresover time, the other concerned withthe internal consistency, or homo-geneity of the constituent items thatform a scale score.
RELIABILITY : STABILITY
Also known as test-retest reliability,an assessment is made of the similar-ity of scores on a particular scaleover two or more test occasions. Theoccasions may be from a few hours,days, months or years apart.Normally Pearson correlation coeffi-cients are used to quantify the simi-larity between the scale scores overthe two or more occasions.
Stability coefficients provide animportant indicator of a test’s likelyusefulness of measurement. If thesecoefficients are low (< approx. 0.6)then it is suggestive that either thebehaviours/attitudes being measuredare volatile or situationally specific,or that over the duration of the retestinterval, situational events have ren-dered the content of the scale irrele-vant or obsolete. Of course, theduration of the retest interval pro-vides some clue as to which effectmay be causing the unreliability ofmeasurement. However, the secondmeasure of a scale’s reliability alsoprovides valuable information as towhy a scale may have a low stabilitycoefficient.
bpRELIABILITY : INTERNALCONSISTENCY
Also known as scale homogeneity, anassessment is made of the ability ofthe items in a scale to measure thesame construct or trait. That is, aparameter can be computed thatindexes how well the items in a scalecontribute to the overall measure-ment denoted by the scale score. Ascale is said to be internally consis-tent if all the constituent itemresponses are shown to be positivelyassociated with their scale score.
The most common measure ofinternal consistency is Cronbach’sAlpha. If the items on a scale havehigh inter-correlations with eachother, and with the total scale score,then coefficient alpha will be high.Thus a high coefficient alpha indi-cates that the items on the scale aremeasuring very much the samething, while a low alpha would besuggestive of either scale items mea-suring different attributes or thepresence of error.
The fact that a test has high inter-nal consistency and stability coeffi-cients only guarantees that it ismeasuring something consistently. Itprovides no guarantee that the test isactually measuring what it purportsto measure, nor that the test willprove useful in a particular situation.Questions concerning what a testactually measures and its relevancein a particular situation are dealtwith by looking at the test’s validity.Reliability is generally investigatedbefore validity as the reliability of atest places an upper limit on thetest’s validity. It can be mathemati-cally demonstrated that a validitycoefficient for a particular testcannot exceed that tests reliabilitycoefficient.
VALIDITY
The ability of a scale score to reflectwhat that scale is intended to mea-sure. Kline’s (1993) definition is “Atest is said to be valid if it measureswhat it claims to measure”.
Validation studies of a test investi-gate the soundness and relevance ofa proposed interpretation of that test.Two key areas of validation areknown as criterion validity and con-struct validity.
VALIDITY : CRITERIONVALIDITY
Criterion validity involves translatinga score on a particular test into aprediction concerning what could beexpected if another variable wasobserved.
The criterion validity of a test isprovided by demonstrating thatscores on the test relate in somemeaningful way with an external cri-terion. Criterion validity comes intwo forms –predictive and concur-rent. Predictive validity assesseswhether a test is capable of predict-ing an agreed criterion which will beavailable at some future time –e.g.can a test predict the likelihood ofsomeone successfully completing atraining course. Concurrent validityassesses whether the scores on a testcan be used to predict a criterionmeasure which is available at thetime of the test –e.g. can a test pre-dict current job performance.
VALIDITY : CONSTRUCTVALIDITY
Construct validity assesses whetherthe characteristic which a test isactually measuring is psychologicallymeaningful and consistent with thetest’s definition.
The construct validity of a test isassessed by demonstrating that thescores from the test are consistentwith those from other major testswhich measure similar constructsand are dissimilar to scores on testswhich measure different constructs.
bqThe OIP is an occupational interestinstrument designed to be usedacross a wide spectrum of careerassessment/guidance situations. Thetotal standardisation sample is basedon 2500+ UK adults made up fromthe following constituent samples:
MANAGEMENT APPLICANTS
A total of 1705 individuals applyingfor a wide variety of managementposts, the data being collected from anumber of companies during 1993-1994. The sample consisted ofapproximately 82% males and 18%females.
POSTAL SAMPLE
582 individuals responded to a largescale postal survey in which theywere asked to complete the OIP. Thequestionnaires were completedduring the early part of 1993. Thissample consisted of representativesof a wide number of occupationsranging from manual labour throughto professional occupations. Thesample comprised approximatelyequal numbers of both sexes.
CHILD CARE APPLICANTS
163 applicants for places on a childcare training program with aNorthern training college completedthe OIP during 1993-1994. Femalesmade up 97% of the sample.
GENERAL APPLICANTS
106 applicants for a wide variety ofgeneral posts completed the OIP aspart of their application procedure.These posts were with a number ofcompanies throughout the UK. Thesample was almost equally dividedbetween the sexes.
5TH YEAR STUDENTS
76 5th Year students from anHertfordshire Comprehensive schooltook part in the initial normative tri-alling of the OIP. The sample con-sisted of almost equal numbers ofboth sexes.
The table opposite provides sum-mary information concerning theconstituent samples of the total stan-dardisation sample of 2556 individ-uals. The total sample consisted of70% males & 30% females. Thetotal age range covered by the stan-dardisation sample was 16-66 years.
STANDARDISATIONPROCEDURES ANDNORMATIVE DATA
br
Sample ID
1
2
3
4
5
Table 1: Standardisation Sample Composition
Males Females
Number
1411
336
158
51
36
Mean Age
31
41
22
29
16
Range
23-55
18-66
18-34
20-45
16-17
Number
293
245
5
55
40
Mean Age
33
35
20
27
16
Range
28-49
21-52
18-22
21-42
16-17
bs RELIABILITY OF THE OIPINTERNAL CONSISTENCY
Internal consistency reliabilities(Cronbach’s Alpha) were computedon samples 2 & 3 as well as for theentire sample. The coefficients arecomputed over both the combinedmales & females for each relevantsample. Table 2 below provides thesecoefficients separately for eachsample and for the entire normativesample.
The mean ‘corrected’ item-totalcorrelations for each scale are alsoreported for each sample. Theseparameters index the average associ-ation between the constituent itemswithin a scale and the scale scoreitself. Each individual item-scalescore coefficient is corrected for the
inflation of the coefficient due to theitem’s inclusion in the scale score. Inaddition, Table 2 provides thenumber of items which make upeach scale.
Table 2 shows that, for the totalsample, all the OIP dimensions haveinternal consistency reliability coeffi-cients of 0.79 or above indicatingthat the test dimensions have anacceptable level of reliability. It canbe seen that the reliabilities also holdup quite well across the two subgroups reported above. The reliabili-ty of these scales compares extremelyfavourably with the reliability coeffi-cients reported in the user manualsfor such tests as the OPQ and 16PF.
btSample 3(N=163)
Sample 2(N=582)
Total Sample(N=2500)
Table 2: OIP Internal Consistencies & Item Total Correlations (ITC’s)
ScaleNeed for VarietyNeed for StabilityNeed for StructureNeed for PeopleNeed for ControlPersuasiveScientificPracticalAdministrativeCaringCreativeLogical
No. of Items101010121010101010101010
Alpha0.770.830.690.750.800.780.820.750.730.700.870.73
ITC0.250.340.180.210.300.270.320.240.220.210.400.23
Alpha0.900.830.790.860.900.850.880.820.860.840.870.83
ITC0.470.350.280.350.490.360.440.320.390.340.410.34
Alpha0.860.830.740.850.880.830.880.810.840.900.870.87
ITC0.380.340.230.340.440.330.440.310.340.470.400.41
ckTHE INTERNAL STRUCTURE OF THE OIP
The inter-correlations between thevarious dimensions of a test are ofinterest as it is important that a test’ssub-scales are relatively independentof each other, thus demonstratingthat they are measuring distinct con-structs.
Table 3 demonstrates that thecorrelations between the OIPPersonal Work Needs sub-scales arefairly modest in size indicating thatthese dimensions are assessing differ-ent personality characteristics. Thereare however some interesting pat-terns of correlations between theseOIP scales. One is the moderatelyhigh correlation between Need forVariety and the Needs for People &Control. This suggests that risk-takers are fairly gregarious peoplewho like to assert their personalityover others.
In addition, the OIP dimensionNeed for Control is positively corre-lated with the needs for Variety,Stability and People. Thus, assertiveindividuals tend to be emotionallystable, extraverted types who are notfrightened to take risks in their per-sonal life. This cluster would beexpected given the nature of theNeed for Control dimension.
Table 4 shows modest correlationsbetween most of the vocational inter-est scales which implies that thescales are indeed measuring fairlyindependent interest areas.
As with the personal work needsthere are a number of interesting,and expected, patterns to be found inthe table. For example there is amoderately strong correlationbetween the Logical and Scientificinterest scales. This is only to beexpected given the emphasis manyscientific disciplines place on logicalanalysis and computational models.Caring correlates fairly well with theArtistic dimension and hardly at allwith Scientific, Practical and Logicalinterests demonstrating thepeople/objects split one would expectfrom these interests.
Table 5 shows that for the mostpart very small correlations existbetween the OIP vocational interestsand personal work needs. This sug-gests that these two parts of the OIPare indeed measuring differentaspects of the personality. Of all theinterest dimensions the Persuasivescale appears to be the most closelyrelated to the personal work needs.Thus an interest in persuasive rolesinvolving convincing communicationis correlated fairly strongly withassertive, extraverted, risk-takingpersonality traits. This is not unsur-prising, as success in a persuasiverole probably to a great extentdepends very much on an individu-als personality. The extravertedqualities indicated by the Need forPeople are also moderately associat-ed with an interest in caring andhelping, once again a not particular-ly surprising finding. There is also atendency for people who express aninterest in logical/computationalareas to be fairly phlegmatic typesable to be assertive, and take chargeof other people.
CONSTRUCT VALIDITY
cl
OIP Interests
1 Persuasive2 Scientific3 Practical4 Administrative5 Caring6 Creative7 Logical
Table 4: Correlations between OIP Vocational Interests (n = 2556)
1
1.00.18.17.23.23.44.30
2
.181.00.54.29.09.13.52
3
.17
.541.00.20.09.12.46
4
.23
.29
.201.00.13.08.53
5
.23
.09
.08
.131.00.38
-.02
6
.44
.13
.12
.08
.381.00.06
7
.30
.52
.46
.53-.02.06
1.00
OIP Work Needs
1 Need for Variety2 Need for Stability3 Need for Structure4 Need for People5 Need for Control
Table 3: Correlations between OIP Personal Work Needs (n = 2556)
1
1.00.25.15.41.43
2
.251.00-.26.35.44
3
.15-.261.00-.02-.23
4
.41
.35-.021.00.52
5
.43
.44-.23.52
1.00
OIP Work Needs
Need for VarietyNeed for StabilityNeed for ChangeNeed for PeopleNeed for Control
Table 5: Correlations between OIP Interests & Work Needs (n = 2556)
Pers.
.44
.38-.09.56.71
Sci.
.18
.25-.02.04.23
Prac.
.32
.37-.14.12.29
Admin
-.01.26
-.14.11.30
Caring
.13
.16
.02
.39
.10
Art.
.26
.05
.14
.28
.20
Log.
.25
.39-.18.17.45
OIP-Pers Persuasive Interests OIP-Nur Caring InterestsOIP-Sci Scientific Interests OIP-Art Creative InterestsOIP-Prac Practical Interests OIP-Log Logical InterestsOIP-Admin Administrative Interests
cmTHE RELATIONSHIP BETWEENOIP & 15FQ
A total sample of 1971 completedboth the 15FQ and the OIP as partof selection and assessment proce-dures with a diverse number oforganisations. The OIP comprisestwo sections, personal work needsand vocational interests. These arereported separately.
Table 6 presents the correlationswith 15FQ and OIP Personal WorksNeeds. For each of the five OIPdimensions, one or more correspond-ing 15FQ correlates is found. OIPVariety is strongly related to 15FQEnthusiastic. OIP Stability is highlycorrelated with all 15FQ anxietyscales. OIP Structure is related to15FQ Detail Conscious and OIPPeople to each of the 15FQExtraversion dimensions. FinallyOIP Control is most closely related to15FQ Assertive.
As might be expected, as 15FQdoes not measure interests, the corre-lations between 15FQ and OIPVocational Interests, reported inTable 7, are only very modest inmagnitude. Only three of the interestareas appear to relate to personalitytraits. People who are interested inPersuasive roles tend to be more out-going, Assertive, Socially Bold andEnthusiastic. There is a small ten-dency for those who are interested inadministrative work to be Detail-conscious. Finally interest in artisticand creative activities is positivelyrelated to 15FQ Intuitive andConceptual, both measures of cre-ative tendencies.
RELATIONSHIP BETWEEN OIP& THE JUNG TYPE INDICATOR
A total sample of 1971 completedboth JTI and OIP as part of selectionand assessment procedures with adiverse number of organisations. Ascan be seen from Table 8 (nextpage), extraversion on the JTI corre-lated quite strongly with the OIPneeds for variety, change and people,exactly those needs which one wouldpredict for Extraverts. Extravertsshowed an interest in Persuasiveroles involving the communication ofinformation as well as in those activ-ities centred on other people.Intuitives, as indicated on the SNscale, showed the need for Varietyand Change which would be expect-ed given the questioning, exploringnature of those people placed at theN end of this dimension. Intuitiveswere also highly interested in Artisticpursuits, again this is in line with thedefinition of Intuitives. Feeling typestended to be low scorers on Stability,a measure of emotional resilience &self-confidence, while scoring highlyon need for Change, which wouldindicate some lack of emotional self-control. There was also a fairly highcorrelation between Feeling typesand Artistic interests, an expressionof the sensitive emotionality ofFeeling types. Finally Perceptivetypes with their emphasis on spon-taneity and flexibility tend to scorehighly on the OIP needs for Varietyand Change. As would be expectedof the spontaneous Perceptives theyshowed a dislike of Administrativetasks such as clerical and financialwork.
cn
15FQ Scale
OutgoingCalm-stableAssertiveEnthusiasticDetailedSocially BoldIntuitiveSuspiciousConceptualRestrainedSelf-doubtingRadicalSelf-sufficientDisciplinedTense-drivenDistortion
Table 6: Correlations between 15FQ and OIP Work Needs (N=1971)
need forVariety
.23
.28
.45
.23
-.21
need forStability
.39
.54
.23
.22
.29
-.27
-.41
-.26
-.39.41
need forStructure
.23
.27
.42
.21
.29
.29
need forPeople
.49
.24
.25
.45
.51
-.51-.33
need forControl
.45
.39
.50
.44
.46
-.22.23
.24
15FQ Scale
OutgoingCalm-stableAssertiveEnthusiasticDetailedSocially BoldIntuitiveSuspiciousConceptualRestrainedSelf-doubtingRadicalSelf-sufficientDisciplinedTense-drivenDistortion
Table 7: Correlations between 15FQ and OIP Vocational Interests
Pers
.44
.30
.42
.47
.57
.16
.26
-.14
-.30.16.22.18
Scient
.13
.14
.13
.14
Pract
.15
.15
-.21
.14
Admin
.15
.22
.29
.15
.23
.17
Nur
.23
.21
.15-.16.16
-.26
Art
.16
.22
.28
.44
.48
.24
Log
.18
.26
.25
.15
.22
.14
.13
.17
.22
coTHE RELATIONSHIP BETWEEN OIP VOCATIONAL INTERESTS AND HOLLAND’S VPI
A sample of 108 undergraduate stu-dents completed both OIP andHolland’s VPI as part of a validationexercise.
As can be observed from Table 9,some very strong, meaningful corre-lations emerge. The VPI Realisticscale correlates strongly with OIPPractical which is as expected. It alsoregisters marginal correlations withOIP Scientific and Logical whichsupports the notion of the Realisticinterest reflecting a technologicalbias. Holland’s Investigative scalecorrelates above 0.7 with OIPScientific, pointing to near equiva-lence in measurement focus. Equally,both the Artistic interest scales inOIP and VPI are correlated at 0.76which would suggest that these twoscales are virtually inter-changeable.The VPI scale Enterprising fails tofind a direct equivalent in the OIP,although it correlates positively withOIP Administrative and Persuasiveand inversely with Scientific, whichappears to reflect what might beexpected as qualities of the entrepre-neur. Finally, VPI Conventional cor-relates with OIP Administrative at alevel which reflects that the contentof OIP Administrative encompassesaspects of financial administrativework which is not part of the VPIscale.
The correlations with VPI person-ality scales (Table 10 above) are notas clear as the previous. Some inter-esting associations are observed. VPISelf-Control correlates negativelywith OIP Variety and Practical.While the former appears to makesense on the basis of OIP Varietyreflecting a need for excitement andeven risk-taking, the explanation forthe latter is not immediately obvious.VPI Masculinity-Femininity corre-lates negatively with Nurturing andArtistic suggesting that those withhigh scores on the Masculinity areless inclined to express preferencesfor these types of activities. VPIStatus registers a moderately highcorrelation with OIP Persuasive, sug-gesting that people who perhaps seethemselves as being able to commu-nicate well and convince others tendto endorse higher status professions.Finally, there exists within the VPIan Infrequency scale, the primarypurpose of which is to examinewhether the respondent may haverandomly or inattentively completedthe questionnaire. This is based onscoring rarely endorsed itemresponses. This scale registers amoderate negative correlation withOIP Artistic, the explanation forwhich is not immediately apparent.
cpOIP Scale
VarietyStabilityStructurePeopleControl
PersuasiveScientificPracticalAdministrativeNurturingArtisticLogical
OIP Scale
VarietyChangeStructurePeopleControlPersuasiveScientificPracticalAdministrativeNurturingArtisticLogical
Multiple RTable 8: Correlations between JTI and OIP(n=1971)
EI
-.21-.23-.15-.57-.24
-.38.13
-.25-.18.10
SN
.16
-.22
.17
.40
TF
-.30-.24
-.13
.15
.24-.10
JP
.22
-.35
-.15
.13
Table 9: Correlations between OIP scales and Holland’s VPIInterest Scales
R
.24
.53
.32
I
.73
.37
.32
A
-.27
.27
.76-.20
S
.38
.66
-.25
E
.24
.26
.36-.35
.42
C
.57
.57 .75 .80 .70 .65 .62
R Realistic S SocialI Investigative E EnterprisingA Artistic C Conventional
EI Extraversion-IntroversionSN Sensing-IntuitionTF Thinking-FeelingJP Judgement-Perception
OIP Scale
VarietyChangeStructurePeopleControlPersuasiveScientificPracticalAdministrativeNurturingArtisticLogical
Table 10: Correlations between OIP and VPI additional scales.
SELFCONT
-.38
.22
-.39
MASCFEM
.28
-.43-.45.32
STATUS
.21
.21
.41
.31
INFREQ
-.25
-.32
cqTHE RELATIONSHIP BETWEEN OIP INTERESTS AND THE ROTHWELL-MILLER INTEREST BLANK
The Rothwell Miller Interest Blankasks respondents to rank ordercareers in the order in which theyinterest them. Careers are presentedin groups of twelve jobs, with eightlists in all. It is usually suggestedthat the top two and bottom two jobsselected reflect the high and lowareas of vocational interest.
Table 11 shows strong relation-ships for similar interests on the twotests. Just as importantly there arenegative relationships betweenincompatible interests. Thus it canbe seen that there is a strong rela-tionship between the OIP Artisticscale and the R-M Aesthetic, as wellas sizeable correlations with Literaryand Musical interests. The OIPArtistic is also negatively associatedwith the R-M Computational andScientific scales, which would beexpected given the nature of thesetwo interest areas. Two R-M interestsfail to correlate well with similarlynamed OIP interests. In the case ofthe OIP Practical scale this shows a
fairly large relationship with the R-MMechanical but not with the R-MPractical. The reasons for this lie inthe definitions of these two scales,the OIP Practical is much moremechanically oriented than craft ori-ented, while the reverse is true of theR-M practical.
There is also a fairly small rela-tionship between the OIP and R-Mpersuasive scales. The reason for thisprobably lies in the way the scalesare constructed on the two tests. TheOIP Persuasive interest scale asksquestions about a person’s liking forvarious persuasive behaviours whilethe Rothwell-Miller simply presentsa list of jobs which are assessed torequire persuasive skills.
cr
OutdoorMechanicalComputationalScientificPersuasiveAestheticLiteraryMusicalSoc. Serv.ClericalPracticalMedical
Table 11: Correlations Between OIP Interests & Rothwell-Miller
Pers.
.21
Sci.
.55
-.32
Prac.
.54
-.49
Admin
-.32
.48
-.31.41
Nurt.
-.41-.59-.31-.37
.55
Art.
-.45-.47
.71
.41
.43
Logical
.51
-.44.30
csRELATIONSHIP BETWEEN OIP AND OPP
A sample of 108 undergraduate stu-dents completed both OIP and theOccupational Personality Profile aspart of a validation exercise.
A number of notable correlationsare evident from Table 12 above,providing particular support forthose OIP scales measuring personalneeds, with less congruence observedwith OIP interest scales. Firstly, bothneed to Control and Persuade (OIPControl and Persuasive) correlatewith OPP Assertive. The 0.65 corre-lation with OIP Control is clearlydemonstrating that this scale is mea-suring a disposition towards forcefultask-orientation. OIP Structure,which assesses need for order anddiscipline correlates negatively withOPP Detailed-Flexible, which is as itshould be. Both OIP Stability andPeople register 0.74 correlations withOPP Phlegmatic and Gregarious,demonstrating that these scales aremeasuring aspects of emotional sta-bility and Extraversion respectively.The only OIP personal work needthat fails to converge with the OPP isVariety. The small tendencies thatare observed (Assertive, Flexible andOptimistic sic. Internal Locus ofControl) are in the expected direc-tion, reflecting a belief in overcomingobstacles, people and disregard fororder and correctness, but no more.
As far as the OIP vocational inter-est scales are concerned, a numberdo find strong congruence with OPP
counter-parts. The most striking isthe -.82 correlation between OIPArtistic and OPP Abstract-Pragmatic. This exceptionally highcorrelation, would be good support ifachieved as an estimate of reliabilityfor a single scale i.e. the same itemsadministered on two occasions. Thisdoes comment perhaps more on theOPP than the OIP. Although OIPitems are most clearly vocationallyorientated, the OPP Abstract-Pragmatic items appear to be cover-ing the same ground, with items thaton the face of it, appear to be morefocused on personal disposition. Thequestion that remains is whether thisscale would be better classified as aninterest than a personality trait.
OIP Practical finds no clear OPPequivalent, although the OIPAdministrative interest scale doescorrelate marginally with OPPDetailed and Pragmatic. OIPNurturing registers an elevated cor-relation with OPP Gregarious andOIP Logical correlates marginallywith OPP Pragmatic andPhlegmatic.
ctOIP Scale
VarietyChangeStructurePeopleControlPersuasiveScientificPracticalAdministrativeNurturingArtisticLogical
Table 12: Correlations between OIP andOPP scales.
ASRT
.24
.32
.65
.50
FLEX
.22
-.51
-.30
TRUS
.41
.21
PHLE
.74
.35
.30
.21
.26
-.29.28
GREG
.74
.31
.26
.44
PERS
.44
.47
.72
.25
CONT
-.30
-.32
EXTE
-.28-.42
-.23
-.29
PRAG
.29
.30
-.82.32
ASRT Empathic-AssertivePERS Genuine-PersuasiveFLEX Detailed-FlexibleCONT Composed-ContestingTRUS Cynical-TrustingEXTE Optimistic-PessimisticPHLE Emotional-PhlegmaticPRAG Abstract-PragmaticGREG Reserved-Gregarious
dkRELATIONSHIP BETWEEN OIP WORK NEEDS & 16PF
A sample of 47 people, all traineecareer officers, completed both theOIP and the 16 Personality Factorquestionnaire. The table below pre-sents the significant correlationsbetween the OIP Work Needs andthe 16PF.
Table 13 provides support for thedefinitions of the OIP Personal WorkNeeds. It can be seen that the Needfor Change scale correlates positivelywith both F (Enthusiastic) and H(Bold), and negatively with G(Expedient). These factors wouldseem to fit well the description of theOIP Need for Change. The OIP sta-
bility scale correlates with a numberof 16PF scales which lend corrobora-tive evidence as to the nature of thisscale. Thus C (Emotionally Stable),O (Self-assured) and Q4 (Relaxed)all suggest a scale which is measur-ing stability. Need for Structure cor-relates highly with G (Conscientious)and Q3 (Following Self-Image) bothof which deal with rule-followingbehaviour. Need for People correlateshighly with F (Enthusiastic), H(Bold) and Q2 (Group Oriented) allof which suggest this OIP scale isconcerned with the Extravert traits.
dlChange
.49-.34.32
Stability
.42
.38
.45
-.31-.59
-.59
Struct
-.63
-.54-.57.36
People
.46
.48
-.35
-.48
Control
.49
-.41
Table 13: Correlations between OIP Work Needs & 16PF
ABCEFGHILMNOQ1Q2Q3Q4FG
dmFACTOR ANALYSIS OF THE OIPSCALES
A factor analysis of the total norma-tive database for the OIP was carriedout to investigate the underlyingstructure of the OIP. An Orthogonalanalysis with Principal Componentsextraction and Normalised Varimaxrotation of the resulting factors wascarried out.
As can be seen from the tablebelow there would seem to be a fairlylogical separation of the various OIPscales across the four factors. Theloadings on Factor 1 suggest thatthis factor is primarily concernedwith control and manipulation ofrelationships. Thus individuals scor-ing high on factor 1 would be highlypersuasive, extraverted, assertivetypes. Factor 2 is concerned withtasks rather than with people.Individuals scoring highly on thisfactor would have little interest inrelationships being much more con-cerned with practical or theoreticalissues. An inspection of the loadingsof Factor 3 would seem to indicatethat this factor is concerned withfairly bureaucratic matters. Thus,people scoring highly on this factorwould be resistant to change, enjoyadministrative duties, dislike takingrisks and be of a fairly phlegmaticdisposition. The final factor is pri-marily concerned with the caring,creative themes. Unlike Factor 1which was basically a manipulative,Machiavellian interest in others,Factor 4 deals with an interest inhelping other people. People high onthis factor would not be as extravert-ed as the Factor 1 type but theirinterest in others would perhaps bemore genuine.
OCCUPATIONAL GROUPS ANDTHE OIP FACTOR STRUCTURE
The above factor structure should,if it is more than a mathematicalartefact, discriminate betweengroups of jobs described by the vari-ous factors. To investigate whetherthis was the case the OIP normativedatabase was searched for jobswhich could easily be described byone of these four categories. Oncefour job groups had been identifiedthe average stanine profile for eachjob compared to the general popula-tion was calculated.
FACTOR STRUCTURE OFTHE OIP
dnOIP Scale
Need for VarietyNeed for StabilityNeed for ChangeNeed for PeopleNeed for ControlPersuasiveScientificPracticalAdministrativeCaringCreativeLogical% Variance Explained
Table 14: OIP (n=2556) factor pattern loadings
I
.67
.52
.74
.81
.80
23.2
II
.32
.84
.76
.49
.7619.6
III
-.47.36-.77
.51
11.7
IV
.35
.83
.69
12.6
doOIP Profile for Persuasive OccupationsThe graph below gives the average profile for jobs classified within theFactor 1 category, which was described as being concerned with those occu-pations dealing with controlling and manipulating others. The profile showslarger than average needs for change, while indicating that emotional stabili-ty is lower than that found in the general population. As would be expectedvocational interest in persuasive roles is higher than generally found, whilean interest in nurturing roles is correspondingly low.
0
1
2
3
4
5
6
7
8
9
CHA STA STR PEO CON PER SCI PRA ADM NUR ART LOG
Figure 1: OIP Profile for Persuasive Occupations
dpOIP Profile for Practical RolesFigure 2 shows the average profile for individuals classified as belonging toFactor 2 occupations –those concerned with tasks rather than with people. Ascan be seen this profile shows a larger than average need for structure, withlower than average needs for people and control. This reflects the nature ofmany practical occupations with their emphasis on structures and detailshaving less to do with other people or the need to control them. This profileshows high levels of scientific, practical and logical interests, all areas inwhich tasks are likely to be considered more important than people. This iscorroborated by the low level of interest displayed in nurturing roles
0
1
2
3
4
5
6
7
8
9
CHA STA STR PEO CON PER SCI PRA ADM NUR ART LOG
Figure 2: OIP Profile for Practical Roles
dqOIP Profile of Bureaucratic RolesThe above figure displays the average profile of those interested in adminis-trative roles. As can be seen there is a low level of need for change in this pro-file, coupled with a high level of need for structure. Such a combinationindicates an individual who would dislike taking risks, requiring a fairlystructured, rule-governed environment. There is also a fairly low level ofneed for control, indicating that such individual might feel more comfortablereceiving orders than giving them. There is a below average interest in practi-cal, scientific pursuits and in nurturing roles. A high level of interest inadministrative matters is shown, as expected, with an above average interestin logical matters.
0
1
2
3
4
5
6
7
8
9
CHA STA STR PEO CON PER SCI PRA ADM NUR ART LOG
Figure 3: OIP Profile of Bureaucratic Roles
dr
0
1
2
3
4
5
6
7
8
9
CHA STA STR PEO CON PER SCI PRA ADM NUR ART LOG
Figure 4: OIP Profile of Caring Roles
OIP Profile of Caring RolesFigure 4 displays the average profile for occupational roles classified asbelonging to the Factor 4 category. As can be seen there is a below averageneed for control and change, combined with an above average need for struc-ture and people. Thus, the work needs suggest an individual who has a gen-uine liking for people and little desire to control them, who requires a fairlystructured, safe environment. The profile shows below average levels of inter-est in persuasive, scientific, practical, administrative and logical roles with ahigh level of interest in nurturing roles. Thus, for these individuals, their pri-mary concern is with the nurturing, caring issues and little interest will bedisplayed in anything which does not relate to these issues.
ds
3BEFORE STARTING THE QUESTIONNAIRE
Put candidates at their ease by giving information about yourself, the purposeof the questionnaire, the timetable for the day, if this is part of a wider assess-ment programme, and how the results will be used and who will have accessto them. Ensure that you and other administrators have switched off mobilephones etc.
The instructions below should be read out verbatim and the same scriptshould be followed each time the OIP is administered to one or more candi-dates. Instructions for the administrator are printed in ordinary type.Instructions designed to be read aloud to candidate incorporate a grey shadedbackground, italics and speech marks.
If this is the first or only questionnaire being administered give an introduc-tion as per or similar to the following example:
“From now on, please do not talk among yourselves, butask me if anything is not clear. Please ensure that anymobile telephones, pagers or other potential distractions areswitched off completely. We shall be doing the OccupationalInterest Profile which has no time limit, however, mostpeople take about 20 minutes. During the test I shall bechecking to make sure you are not making any accidentalmistakes when filling in the answer sheet. I will not bechecking your responses.”
WARNING: It is most important that answer sheets do not go astray. Theyshould be counted out at the beginning of the test and counted in again at theend.
ADMINISTRATIONINSTRUCTIONS
ekContinue by using the instructions EXACTLY as given. Say:
DISTRIBUTE THE ANSWER SHEETS
Then ask:
“Has everyone got two sharp pencils, an eraser, some roughpaper and an answer sheet.”
Rectify any omissions, then say:
“Print your surname, first name and title clearly on the lineprovided, followed by your age and sex. Please inserttoday’s date which is [ ] on the ‘Comments’ line”
Walk around the room to check that the instructions are being followed.
WARNING: It is vitally important that test booklets do not go astray. Theyshould be counted out at the beginning of the session and counted in again atthe end.
DISTRIBUTE THE BOOKLETS WITH THE INSTRUCTION:
“Please do not open the booklet until instructed.”
Remembering to read slowly and clearly, go to the front of the group and say:
“Please open the booklet and follow the instructions for thistest as I read them aloud.” (Pause to allow booklets to beopened)
This is a questionnaire concerning your interests,preferences and feelings about a range of things.
You are asked to rate yourself on a scale from 1 to 5 oneach question. When you have chosen the answerappropriate for YOU, record this by blackening thecorresponding box on the answer sheet.
For example:
Ratings:
1 2 3 4 5Strongly Agree In Disagree Strongly
Agree between Disagree
1. I like to watch the news on TV.
elIf you strongly agreed with this statement, you would fullyblacken box 1 against question 1 on your answer sheet.”
Check for understanding of the instructions so far, then say:
“When answering the questions please remember thefollowing:
1. Do not spend too much time pondering over the answerto each question. The information given in a questionmay not be as full as you would wish, but answer as bestyou can.
2. Please try to avoid the middle (In between) answerwherever possible.
3. Be as honest and truthful as you can. Don’t give ananswer just because it seems to be the right thing to say.
4. Make sure you answer every question, even those whichdo not seem to apply to you.
5. If you wish to change an answer, please erase it andinsert your new answer.”
Then say very clearly:
“Is everybody clear about how to do this test?”
Deal with any questions appropriately, then say:
“Please begin”
Answer only questions relating to procedure at this stage, but enter in theAdministrator’s Test Record any other problems which occur. Walk aroundthe room at appropriate intervals to check for potential problems. Wheneverybody has completed the questionnaire:
COLLECT ANSWER SHEETS & TEST BOOKLETS, ENSURING THATALL MATERIALS ARE RETURNED (COUNT BOOKLETS & ANSWER SHEETS)
Then say:
“Thank you for completing the Occupational InterestProfile.”
4REFERENCESAllport, G. W. (1934) Personality: APsychological Interpretation. NewYork: Holt, Rinehart & Winston.
Budd, R. J. (1991). Manual for the15FQ. Letchworth, Herts: PsytechInternational.
Budd, R. J. (1991). Manual for theOPP. Letchworth, Herts: PsytechInternational.
Budd, R. J. (1991). Manual for theJTI. Letchworth, Herts: PsytechInternational.
Campbell, D. P. (1971). Handbookfor the Strong Vocational InterestBlank. Stanford: Stanford UniversityPress.
Cronbach, L.J. (1951). Coefficientalpha and the internal structure oftests. Psychometrica, 16, 297-334
Holland, J. L. (1975). Manual forthe Vocational Preference Inventory.Palo Alto, CA: ConsultingPsychologists Press.
Kline, P. (1993). Personality: ThePsychometric View. London,Routledge.
Kuder, G. F. (1956). Examiner’sManual for the Vocational Form-C.Chicago, Illinois: Science ResearchAssociates.
Miller, K.M. (1968). Manual for theRothwell-Miller Interest Blank.Windsor, Berks: The NFER-NelsonPublishing Company.
Galton, F. (1884). HereditaryGenius, London MacMillan.
