Stratified SamplingStratified Sampling

• First we divide the pop by certain characteristics

Eg. Gender, age, etc

• based on key independent variables

• each sub-population is called stratum

• Each stratum is mutually exclusive set of elements

Cont’dCont’d• finally using SRS or SS, we sample from

each stratum• Used to examine the r/ship b/n

independent (criteria for stratification) and dependent variable;

• To make comparisons among sub-pop• And used to reduce sampling error

*prior information about the pop is required

Cont’dCont’d

• Disproportionate Stratified Sampling- equal sample size from each stratum

• Proportionate Stratified Sampling- proportional sample size from each stratum

• Note: Use SS only if there is significant difference across the strata

Multi-Stage Cluster SamplingMulti-Stage Cluster Sampling

• For population without exhaustive list (SF)

• Or when it is impossible to compile a complete list of the elements (SF)

• Involves sampling of natural clusters

– Eg. Schools, kebeles, industries, etc

Cont’dCont’d

• Followed by selection of elements from the clusters using SRS or SS– Eg. Addis Ababa households’ mode of

transportation

• Involves listing and sampling at d/t stage

• It involves two or more sampling error

Stratified Multi-stage Cluster Stratified Multi-stage Cluster SamplingSampling

• Involves grouping of clusters with similar characteristics;

• Then selecting clusters from each group of similar clusters;– Eg. Lideta Sub-city poverty study

• Stratification can take place at each stage of sampling

Probability Proportionate to Size Probability Proportionate to Size (PPS) Sampling(PPS) Sampling

• In most cluster sampling small clusters tend to disproportionately represented

• To avoid this we give equal chance of selection

Method– Giving each cluster chance of selection

proportionate to its size– Then selecting equal sample size from each

cluster

Cont’dCont’d

• Illustration: suppose we want to sample 1/10th of 5 clusters, in which the clusters have 50,100, 200, 300 and 400– We will give a proportion of 1, 2, 4, 6 and 8

respectively

• PPS is used to– Permit selection of more clusters– Ensure representation of large clusters– Equal chance of being selection to the pop

Cont’dCont’d

• PPS is applied under 3 conditions:– When dealing with unevenly distributed

clusters;– With large sample size w/c can be broken into

clusters; and– When we have data on the proportion of each

cluster.

Sample SizeSample Size

• Sample size depends on

– heterogeneity of the pop, strata or cluster;

– size of the sub-group

– precision• SEM=sd/√n

• The larger the sample size the the lower the sampling error

Non-probability samplingNon-probability sampling

• Purposive or judgmental sampling: Sample selected because of their unique position in the pop understudy;

• Quota Sampling: selected to represent a certain characteristics or group in a pop.

Measurement and MeaningMeasurement and Meaning

• Concept: is a mental image that summarize similar observations, idea,– Eg. Poverty, slum, etc

• Conceptual Definition: specification of the meaning of each concept in a research to enable measurement– Eg. Slum is ‘a heavily populated urbanarea characterized by substandard housing and

squalor’.

Cont’dCont’d

• Operational Definition: a definition by which we make the concept measurable, using indicators.– Eg. Slum- • inadequate access to safe

water;• inadequate access to sanitation

and other infrastructure;• poor structural quality of

housing;• overcrowding;• insecure residential status.

Level of MeasurementLevel of Measurement

There are 4 levels to measure variables.• Nominal Variable: mutually exclusive

categories. With no ordering.Eg. Sex, marital status, etc

• Ordinal Variable: categories ordered or ranked in sequential manner.

Eg. Class rank, social class

• Interval-Ratio Variable: logical, ordered and defined in terms of a standard unit of measurement.

Cont’dCont’d

• Usually have a zero point- i.e. absence– Eg. Age, land area, distance from city-center

etcDiscrete variable- integer number of values

eg. Age, family sizeContinuous Variable- assume a decimal

number of values. Eg. Distance, area, etc Note: the statistical analysis that we apply

differs to each level of measurement and to the two types of variables.

Instrument DesignInstrument Design

• Questionnaires are set of questions or statements which we used to gather data in survey research.

• There are two types of questions Open-ended- respondent gives his own answer

Eg. What is your attitude towards Addis trans?Close-ended- respondents selects from the

choices providedEg. How do you grade urban trans in AddisGood Fair Bad

Guide to Question ConstructionGuide to Question Construction

• Respondents must be competent to answerEg. What kind of planning technique should AACA

apply?

• Use vocabulary that respondents can understand.Eg. What issues should be considered in urban development strategy?

• Make items clear- avoid ambiguous questions.– Eg. Do you live near Mekato?

How often do you visit a doctor?

Cont’dCont’d

• Avoid Negative Items- respondents might agree with the –ve one while they mean +ve one. Eg. Should not the AACA invest on

infrastructure development?

• Avoid Double Barreled Questions- two questions in one questionEg. What is your opinion about the urban policy

and its implementation in Ethiopia?

Cont’dCont’d

• Format questions in a sequential order and bring together similar questionsEg. SD, Mig. History, family condition, living condition

and finally empl’t condition • Avoid biased items or labels

Eg. Fascist, racist, fundamentalist, etc• Contingent questions should be asked to the

relevant respondents.Eg. Are you married?

If yes, does your spouse have a job? How old are you?

Cont’dCont’d

• The purpose of the research should have to be clearly indicated in the beginning of the questionnaire

• General and specific instruction of the questionnaire should have to be clearly indicated

Cont’dCont’d

There are two types of questionnaires

2. Self-administered – filled by the respondent him/herself;

3. Enumerator administered- filled by an interviewer.

Other methods of data collectionOther methods of data collection

• Sample survey enables us to collect data from large amount of respondents using a representative sample

• But its broad coverage make to gather shallow data.

• When we want to collect in-depth information we use:– In-depth interview;– Focus group Discussion; and other methods

In-depth InterviewIn-depth Interview

• Used to collect detailed information using semi-structured interview guide

• The guide is set of generic open ended questions and probing questions

• The guide only lead the flow of the interview• Probing is basic tool in this method

• Eg. What do you know about low cost housing?• Probe • LCH vis-à-vis affordability• LCH vis-à-vis efficiency• LCH vis-à-vis quality

Cont’dCont’d

– Interviewee is given freedom of expression in his own words

– Enable to collect depth information on our research topic

– Usually used with experts, officials, knowledgeable community members, etc

Cont’d Cont’d

• Taking note and recording the interview is crucial

• Disadvantage:– Heavily influenced by the interviewer skill; and

– Difficult to compare responses in a rigorous way.

Focus Group DiscussionFocus Group Discussion

• Used to gather information from a discussion of a group by giving them a topic of discussion

• Group interaction b/n respondents will stimulate richer responses

• The interviewer can observe the discussion and understand their feeling, behaviors, attitudes, etc

• Usually have 6-12 members and a moderator, but a group size of 8 is preferable

• The moderator is expected only to raise topic of discussion and facilitate the discussion

Cont’dCont’d

• The group should be a homogeneous group and it is better if they are acquainted

• If the FGD is handled by a skilled moderator it enables to generate detailed and valid data

• The moderator should control the flow of the discussion using a checklist

• In FGD also probing is important• And the moderator has to take note and use a

tape recorder

The Research PaperThe Research Paper

1. Finding and narrowing the Problem– Select the general topic or issue of research

(from the literature or from our experience);– Review the evidence or literature review

• Identify the knowledge gap

– then we make the research problem precise– every research report should have to clearly

state the research problem in the beginning– Research problem is the k’ge gap to be filled

by the research not social problem

2. Formulating Research 2. Formulating Research Questions Questions

• This are question that the research is going to address

• After clearly setting the RP, we will split the RP into specific answerable research questions– Eg. RP- the K. 10 housing condition

• How is the structural conditions of the houses in the kebele?

• What services and amenities does the residents receive?

• How is the provision of basic infrastructure in the kebele?

3. Composing the Paper3. Composing the Paper

• Academic research report should have to be organized in a manner – Introduction-literature review-methods-result-

conclusion-recommendation

• Introduction- describes related research and explains what your work contributes and why it is important. • It sketches out the objectives, research

questions, hypothesis, scope and organization of the report.

Cont’dCont’d

b) Literature Review- presents the summary of theoretical and empirical findings related with the research topic

c) Methods- this section describes each steps that the study applied in collecting and analyzing the data.– it presents the methodology used, the survey design,

the sampling technique applied, the sample size, the composition of the sample and methods of data analysis.

– In addition, the characteristics of the population is described.

Cont’dCont’d

• Result- should summarize the data and the inferences drawn – It should have to answer the research

questions raised in the introduction– It should include tables and figures to explain

the variables understudy– The result section should be sub-divided into

sub-topics and arranged in an organized manner

– The result should critically analyzed using other evidences and theories

Cont’d Cont’d

– Draw the conclusion from your findings and discuss the possible significance of your findings (recommendation)

– And indicate areas of further research

EditingEditing

The research report should be readable, therefore we should have to make proper editing work before submitting the report.

• Word Choice- avoid undefined adjectives.Eg. Deep, wonderful, near, many, little

• Logical connection with sentences- there should be a logical flow of sentences in a paragraph.

- There should have to be coherence b/n sentences.

Cont’dCont’d

• Avoid to be & passive voice- verb to be (is, was, were, will be) and passive voice makes our description static.

• Avoid informal language- conveying our finding in an informal language makes to seem thoughtless.– Eg. Really was not upset, didn’t, ain’t, all of a sudden

etc

• Keep your summary, paraphrase and quotation as short as possible and harmonize the quote into your paper

DocumentationDocumentation

• Every works quoted or paraphrased from other sources should be properly cited.

• We use in-text citation (the new MLA) method.– Eg. Modern urban planning has arisen in

response to social and econ problems (Neil 56) or

– According to Neil …(56)

Cont’dCont’d

• We can also use Author-Date system– Eg. Modern urban … (Neil, 2004:56) or

According to Neil … (2004:56)

ReferencingReferencing

• You should have to enlist every material you used in the bibliography section.

• Book– Neil, William J.V. (2004) Urban planning and Cultural

Identity. London: Routledge

• Books with editor

• Journal– Morello, Jorge (2000)’Urbanization and Ecology’. In

Third World Planning Review, Vol. 22 No. 4, 2000, pp 119-132