2.Data Collection and Management 20th Dec 2011

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Dr Tin Myo Han

Medical Statistics Unit, Kulliyyah of Dentistry

IIUM


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Data collection and Validity of Research

Data collection tools forQuantitative study

Development of Questionnaires

1/4/2012Data collection & Management 2

Data Management

Data Management Process forQuantitative

study Take home Message

Assignment for students


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INTERNAL

VALIDITY


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Questionnaires, Format

Instruments and Materials


Validity of

Questionnaires

Standardization of Data collectinginstruments


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Questionnaires

-self-administered,

- face to face Interview ,

- filling form/format

Instruments & Materials Procedures to

measure ( BP, Hb%, tooth size)

-Clear Instruction ,-Guideline for Interview

- make a consensus

( to reduce inter-reviewers variation (bias)

Standard Operating Procedures (SOP)

( clinical trials & Basic science)


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Data entry

Data cleaning

Data analysis ( includes in the proposal)

Error :writing , typing error, coping error

Appropriate statistical tests ( based on types of data )


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1.the process of preparing and collecting data

that is both defined and accurate.


2.the process of gathering and measuring

information on variables of interest, in an

established systematic fashion that enables one to

answer stated research questions, test hypotheses,

and evaluate outcomes.

3. capturing, recording, validating and editing data

forcompleteness and accuracy


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Questionnaires

data collection format for

assessment of oral health status

data collection format for

interventional study


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Based on objectives of the study



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Choose/create a theoretical framework Conceptual framework

Identify the predisposing factors( causal factors) and outcome (effect)measures

Plan for the data analysis


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theoretical framework Conceptual framework assists to describe, explain and predict a

behavior oroutcome It also assists to identify relationship between

variables

It reduces the chance of excluding important

variables


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Theoretical structure of assumptions,

principles, and rules that holds togetherthe ideas comprising a broad concept


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Assessment on effectiveness of Oral Hygiene

Education session provided by 4th year dental

students at Students Poly Clinic, Kulliyyah of

Dentistry 2011-2012".



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Knowledge,Attitude &Oral Hygiene

Practices

Outcomes

Exposure

Effectiveness

OHE session

By 4th yearDental students

v

Socio-demoeconomic

status

How to

measure( Indicators)

Peer , family

support

Accessibility &

availability ofOH materials

( HE Materials ,Tooth paste,

Tooth brush

Others?

Factors


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Objective

1. To identify socio-demographic and economic backgroundof respondents

2. To compare oral Hygiene Knowledge of Patients beforeand after OHE session

3. To compare attitude of the patients on proper OH practicesbefore and after OHE session

4.To compare oral hygiene practices of the patients beforeand after OHE session

5. To compare OH status (plaque score??? ) of patientsbefore after OHE session

6. To find out gender and economic influences on OHPchanges of patients

7. To assess influences of accessibility and availability of OHmaterials on OHP changes of patients


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Objectives Questionnaires

& Format

Variables Operational

Definition

Measurement

scale

1.Socio-demographic

and economic

Q 1-5 Age, sex, education,

occupation, income

ect.

????? ?????

2. Knowledge

on OHP

Q 6-20 ???? ???? ????

3. Attitude on

OHP

Q 21- 26 ???? ????? ????

4.OH Practices Q/ format

27-37

???? ????? ????

5. OH status Format

38-45-Plaque score

-???

??? ????

6 & 7

( Inferential

Statistic)

Based on data from Objective -1&4


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Anticipate the data analysis

Think about how you would like to summarizethe data ( dummy tables)

How you analyze the data determines the kindof data you collect

( Categorical, Nominal, Numerical data)

Think about response burden.

Avoid just-in-case syndrome (more is notnecessary better)


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Variable No %

Age Group (yr)

20 30

31-4041-50

51-60

>60

Min- , Max, Mean SD

Sex

Male

Female

Education

IlliterateBasic educationMiddle

High

Graduate



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Variable No %

Knowledge ( 15Qs)

poor ( 0- 5)

Fair ( 6-10)High ( >10)

Min- , Max Mean SD (score)

Attitude ( 5 Likert scale)

Strongly agreeagree

Neutral

Disagree

Strongly disagree

Practices ( 10 Qs)

Goodacceptablelikely acceptable

unacceptable

Min- , Max Mean SD ( score)



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Status Knowledge level Total

High Fair Poor

Before OHP session

After OHP

Significant test X2 P


Status Knowledge level Total

min max mean SD

Before OHP session

After OHP

Significant test pair t = P =


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Monthly total Income of Patients ( RM)

OHP changes ( score) of the patients ( Before)

Fig :Correlation between OHP ( score) of the patients and their monthly total income

r = p=


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A good questionnaire:

Assist to collect data to answer the researchquestion

includes all important independent (predisposingfactors) and dependent variables (outcomes)

gathers valid information (what it meant to ask)

gathers reliable information (repeatable)

is easy to answer by respondents (user-friendly)


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Contents of a questionnaire

Predisposing factors (independent variables):

patient/practitioner/practice socio-demograghic

profile/background patients clinical profile

exposure ( HE session, tooth extraction, BMI )

Outcome measures (dependent variables)

E.g. satisfaction, behavior, morbidity, mortality

changes of Hb%, BP , Knowledge , attitude,

practices


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Structure

MCQ, Open question, SBA, Fill in blank,

Format forClinical/ experimental findings

Format and language:

font size and style

readability

text flow instruction clearity; (eg, Please choice one

or more/ Please circle one or more )


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Beware of:

double-

barrel questions leading questions

sensitive questions

language inconsistency


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Validating a questionnaire



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Always get some one to proofread the

questionnaire Supervisor


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Face validity

Content validity Criterion validity

Theoretical validity


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The extent of questionnaire validation

depends on:

the purpose of the study the resources and time frame

previous validation


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Does the respondent give the same answer with

repeated testing with the same

questionnaire/interviewer? (intra-rater reliability)

Does the respondent give the same answer if the

questionnaire is administered by different

interviewers? (inter-rater reliability)

Does the respondent give the same answer whetherit is self-completed or interviewer administered?


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Is the question ambiguous?

Should the questionnaire beself-completed or interviewer-assisted?


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Be clear about the research question

Determine the dependent and independentvariables

Capture data with the analysis in mind think

how you are going to summarize the data

Arrange the questions in a logical manner

Use simple language and avoid confusing

questions/statements Pilot test the questionnaire to ensure validity and

reliability


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Use an established questionnaires if there is one


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Management :is the activity of gettingthings done with the aid of people andother resources.


Data: the raw material of statisticsQuantitative data Qualitative data

Data Management: Managing data(data Mining) into Meaningful information.


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Datahandling &recording

Data coding& Cleaning

Dataentering

Data

cleaning

DataC

hecking

Data

calculation

Practices SPSSHands on training-

in Computer session


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First, think aboutyour data in terms ofwhat kind of data itis!

(continuous, discreteand ordinal)

Second , specify the

type of a variables

Recording inQuestionnaires andobservational form



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Create new

variables using

compute and

recode



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Every study should be

accompanied by a code

book that describes each

variable by name accordingto the type of data ,the units of

measurement , the purpose of

collecting it and its relationship

to other data.

This code book should be kept

in a separate file from the data

itself and should be available

to all researchers on the study.



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Variable Variable

name

Variable Value

( Code)

Measurement

Identification No

of student

code 1----- 36 Discrete

numerical

Age ( completed

age)

age 20- 25 year

Sex Sex 1= Male

2= Female

Nominal/

Categorical

Marital status Marriage e.g 1 = Single

2 = Marriage

Nominal

Race Race 1 =Malay

2 = Chinese3 = India

4 = Others

Norminal


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Each of these has advantages and disadvantages

Before you decide on which ones to use


Types Name of Soft-ware

plain text files ;spreadsheets

Excel

database programs Access or MySQL

statistics packages SAS, SPSS, Stata orMinitab and Epi info


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Sorting in a spreadsheet

Backups: Data files should be stored on drivesthat are backed up regularly

Consistency: Consistency in data entry iscrucial.( F/M or1= Male, 2= female0

Units of measurement: Units formeasurements should be clearly identified

whenever possible.



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Missing value

Unintended missing

values: Do not useblanks to represent

zero because they

could easily bemistaken as missing

values.



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Manual ( small data set)

soft-ware

Generate frequency

tables

General histogram fornumerical ( continuous)data

Generate descriptive

statistics for data setincluding measure ofcentral tendency anddispersion



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Common procedures:

Eyeballing raw data

Frequency table

Descriptive data

Box and Whisker plot

Histogram

To find out outliers and

extreme values



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You don't need to understand the

underlying calculusbut you do need to know

descriptive and inferential

statistic and how to interpret it.


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A questionnaire is the key data collection

instrument in quantitative research

Having a theoretical framework and

planning the data analysis in advance are

essential for designing a good questionnaire

A valid, reliable and user-friendly

questionnaire is the key to a successful data

collection


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Data collection and Management are important forinternal validity of the research

Proper data collection methods and tools should be

selected for respective study designs .

Regarding structuring of questionnaires,

background academic, socio-economic status of

sample population( respondents) and possible bias

should be considered.

Each and every questionnaire should be tested in pilot-

survey to verify its structures and validity.



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Draw a conceptual frame workfor your research

project

Set aim and specific objectives

List data collection tools for your research project

Structure a questionnaires or a format to collect

data for your research project

Draw a dummy tables

Set data analysis plan



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2.Data Collection and Management 20th Dec 2011

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