Chapter: # 12Chapter: # 12Chapter: # 12Chapter: # 12Data Analysis and Data Analysis and

I t t tiI t t tiInterpretationInterpretation

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Getting Data and Ready for Getting Data and Ready for AnalysisAnalysisAnalysisAnalysis

Editing data.Editing data.Handling blank responses.Handling blank responses.Handling blank responses.Handling blank responses.Coding.Coding.CategorizingCategorizingCategorizing.Categorizing.Entering data.Entering data.

Editing DataEditing Data

Data have to be edited, especially when Data have to be edited, especially when they relate to responses to openthey relate to responses to open--ended ended

ti f i t i dti f i t i dquestions of interviews and questions of interviews and questionnaires, or questionnaires, or unstructured unstructured observationsobservationsobservationsobservations..Checking Incompleteness and Checking Incompleteness and inconsistencyinconsistencyinconsistency inconsistency

Handling Blank ResponsesHandling Blank Responses

Filling Midpoint (interval scale) mean (allFilling Midpoint (interval scale) mean (allFilling Midpoint (interval scale), mean (all Filling Midpoint (interval scale), mean (all respondent in the particular question or respondent in the particular question or particular variable answer of the particularparticular variable answer of the particularparticular variable answer of the particular particular variable answer of the particular respondent), random number or linear respondent), random number or linear interpolation, or ignoredinterpolation, or ignoredPopular mid point and ignoredPopular mid point and ignored25% unanswered throw it out25% unanswered throw it out

CodingCoding

If for some reasonIf for some reason this scanningthis scanning cannotcannotIf for some reason If for some reason this, scanning, this, scanning, cannot cannot be done, then it is perhaps better to use a be done, then it is perhaps better to use a coding sheet fist to transcribe the data coding sheet fist to transcribe the data ggfrom the from the questionnairequestionnaire10% should be checked using random 10% should be checked using random ggsamplingsampling

CategorizationCategorization

Set up a scheme for categorizing the Set up a scheme for categorizing the variables such that the several items variables such that the several items

i t ll di t ll dmeasuring a concept are all grouped measuring a concept are all grouped together.together.

Entering DataEntering Data

If questionnaire data are not collected onIf questionnaire data are not collected onIf questionnaire data are not collected on If questionnaire data are not collected on scanner sheets, which can be entered scanner sheets, which can be entered directly into the computer as a data file thedirectly into the computer as a data file thedirectly into the computer as a data file, the directly into the computer as a data file, the raw data will have to be manually keyed raw data will have to be manually keyed into the computer.into the computer.

Data AnalysisData Analysis

Basic objectives in data analysis.Basic objectives in data analysis.Basic objectives in data analysis.Basic objectives in data analysis.Feel for the data.Feel for the data.testing goodness of datatesting goodness of datatesting goodness of datatesting goodness of dataReliability.Reliability.ValidityValidityValidity.Validity.Hypothesis testing.Hypothesis testing.

Basis Objective in Data AnalysisBasis Objective in Data Analysis

G tti f l f th d tG tti f l f th d tGetting a feel for the data.Getting a feel for the data.Testing the goodness of data.Testing the goodness of data.Testing the hypotheses developed for Testing the hypotheses developed for the research.the research.

Feel for The DataFeel for The Data

W f l f th d t b h kiW f l f th d t b h kiWe can a feel for the data by checking We can a feel for the data by checking the central tendency and the dispersionthe central tendency and the dispersion..O tli lit li it d thO tli lit li it d thOutlier, normality, linearity and other Outlier, normality, linearity and other testing that relates to the technique testing that relates to the technique intended usedintended usedintended usedintended used

Testing Goodness of DataTesting Goodness of Datagg

Th li bilit d lidit f thTh li bilit d lidit f thThe reliability and validity of the The reliability and validity of the measures can now be testedmeasures can now be tested..

ReliabilityReliability

Cronbach’s Alpha:Cronbach’s Alpha:A reliability coefficient that indicates how A reliability coefficient that indicates how well the items in a set are positively well the items in a set are positively correlated to one another.correlated to one another.SplitSplit--Half Reliability:Half Reliability:Another measure of consistency reliability Another measure of consistency reliability used in specific situations. used in specific situations.

Reliability Reliability (cont.)(cont.)

Parallel Form Reliability:Parallel Form Reliability:Wh hi h l i bWh hi h l i bWhen a high correlation between two When a high correlation between two similar forms of a measure.similar forms of a measure.T tT t t t R li bilitt t R li bilitTestTest--retest Reliability:retest Reliability:Can be established by computing the Can be established by computing the correlation between the same testcorrelation between the same testcorrelation between the same test correlation between the same test administered at two different time administered at two different time periodsperiodsperiods.periods.

ValidityValidity

Factorial Validity:Factorial Validity:yyCan be established by submitting the Can be established by submitting the data for factor analysis. data for factor analysis. CriterionCriterion--Related Validity:Related Validity:Can be established by testing for the Can be established by testing for the

f th t diff ti tf th t diff ti tpower of the measure to differentiate power of the measure to differentiate individuals who are known to be individuals who are known to be different.different.

Validity Validity (cont.)(cont.)

Convergent Validity:Convergent Validity:g yg yCan be established when there is a high Can be established when there is a high degree of correlation between two different degree of correlation between two different

di t thdi t thsources responding to the same measure.sources responding to the same measure.Discriminant Validity:Discriminant Validity:C b t bli h d h t di ti tlC b t bli h d h t di ti tlCan be established when two distinctly Can be established when two distinctly different concepts are not correlated to each different concepts are not correlated to each other.other.

Hypothesis TestingHypothesis Testing

Once the data are ready for analysis theOnce the data are ready for analysis theOnce the data are ready for analysis, the Once the data are ready for analysis, the researcher is ready to test the researcher is ready to test the hypotheses already developed for thehypotheses already developed for thehypotheses already developed for the hypotheses already developed for the study.study.

Data Analysis and InterpretationData Analysis and Interpretation

D t l i d i t t ti fD t l i d i t t ti fData analysis and interpretation of Data analysis and interpretation of results may be most meaningfully results may be most meaningfully explained by referring to a businessexplained by referring to a businessexplained by referring to a business explained by referring to a business research project.research project.

R h D i E l iR h D i E l iResearch Done in Excelsior Research Done in Excelsior EnterprisesEnterprises

Excelsior enterprises is a mediumExcelsior enterprises is a medium sizedsizedExcelsior enterprises is a mediumExcelsior enterprises is a medium--sized sized company, manufacturing and selling company, manufacturing and selling instruments and supplies needed by theinstruments and supplies needed by theinstruments and supplies needed by the instruments and supplies needed by the health care industry, including blood health care industry, including blood pressure instruments, surgical instruments, pressure instruments, surgical instruments, dental accessories, and so on.dental accessories, and so on.

Some Preliminary StepsSome Preliminary Stepsy py p

C tC tCompute.Compute.Recode.Recode.Categorize variables.Categorize variables.Replace missing values.Replace missing values.

Checking The Reliability of Checking The Reliability of Measures: Cronbach’s AlphaMeasures: Cronbach’s Alphapp

The interitem consistency reliability or the The interitem consistency reliability or the Cronbach’s Alpha reliability coefficients of Cronbach’s Alpha reliability coefficients of th fi i d d t d d d tth fi i d d t d d d tthe five independent and dependent the five independent and dependent variables were obtained.variables were obtained.

Obtained Descriptive Statistics: Obtained Descriptive Statistics: Frequency DistributionsFrequency Distributionsq yq y

Frequency distributions were obtained for Frequency distributions were obtained for all the personal data or classification all the personal data or classification variablesvariablesvariables.variables.

Descriptive Statistics: Measures of Descriptive Statistics: Measures of C t l T d i d Di iC t l T d i d Di iCentral Tendencies and DispersionCentral Tendencies and Dispersion

Descriptive statistics such as maximum, Descriptive statistics such as maximum, minimum, means, standard deviations, minimum, means, standard deviations, and variance were obtained for the and variance were obtained for the intervalinterval--scaled independent and scaled independent and dependent variablesdependent variablesdependent variables.dependent variables.

Inferential Statistics: Pearson Inferential Statistics: Pearson C l tiC l tiCorrelationCorrelation

The Pearson correlation matrix obtained The Pearson correlation matrix obtained for the five intervalfor the five interval--scaled variables.scaled variables.

Use of Expert Systems in Choosing the Use of Expert Systems in Choosing the Appropriate Statistical TestsAppropriate Statistical TestsAppropriate Statistical TestsAppropriate Statistical Tests

The statistical navigator is an expert system The statistical navigator is an expert system that recommends one or more statistical that recommends one or more statistical procedures after seeking information on the procedures after seeking information on the goals and the datagoals and the datagoals and the data.goals and the data.Expert systems can also be used for making Expert systems can also be used for making decisions with respect to various aspects of the decisions with respect to various aspects of the research design: nature of study, time horizon, research design: nature of study, time horizon, type of study, study setting, unit of analysis, type of study, study setting, unit of analysis, sampling design, data collection methods.sampling design, data collection methods.p g g ,p g g ,