Indexes and Scales Content validity Achieved by including
Indexes and Scales
Content validity Achieved by including all the dimensions of a concept Most non-demographic variables require more than one measure
Composite Methods Used pre-dominantly in quantitative studies Indexes and Scales allow a summary of several measure of the same concept
Scales Reflect degree of the variable Give more information about the concept Especially good for measuring attitudes
Sample Likert-Scale Questions Rate each item on the scale shown to indicate your level of agreement: I believe in the Bill of Rights. agree uncertain disagree strongly disagree I think that everyone should vote. strongly agree uncertain Most politicians cannot be trusted. strongly agree uncertain
Scales More difficult to code than indexes Coding considerations desirable range weighting
Sample Scale of Job-Related Depression I feel down-hearted and blue often never sometimes rarely never I find myself restless and can’t keep still often rarely I get tired for no reason often sometimes rarely never I am more irritable than usual often sometimes
Sample Scale of Political Involvement I think that everyone should vote. strongly agree disagree strongly disagree uncertain disagree strongly disagree Joining a political party should be mandatory. strongly agree uncertain Most politicians cannot be trusted. strongly agree uncertain disagree strongly disagree All votes should be counted. strongly agree uncertain
Different Types of Scales Bogardus Social Distance Scale Thurstone Scales Likert Scales Semantic Differential Guttman Scaling
Indexes Usually use a number of questions about the same thing Answers can be “scored” and added up to produce a total “score” for the concept
Items Measuring School Violence and Delinquency* Question wording 1. Have you been suspended? 2. Have you hit another student? 3. Have you hit a teacher? 4. Have you threatened another student? 5. Have you threatened a teacher? 6. Have you stolen something from someone? 7. Have you carried a weapon? 8. Have you used drugs or alcohol? 9. Have you sold drugs? 10. Have you been caught fighting with another student? 11. Have you been involved in gang fights? 12. Have you been caught fighting with a teacher? 13. Have you been suspended for fighting? * Robber, M. L. (2000). Scary Schools : Specifying General Strain Theory.
Developing a Survey Instrument Use clear language and explicit instructions Types and number of questions will depend on the purpose and the type of survey planned Types of items Open-ended items Multiple-choice Yes items / No items be mindful of lack of information here
Guidelines for Writing Survey Questions Items should be clear Avoid Double-Barreled Questions Respondents Should be Competent Questions Should be Relevant Short Items are Best Avoid Negative Items Avoid Biased Items and Terms
Sample Multiple-Choice Questions How frequently do you take a sick day from work? Identify the issue that you believe is most critical to this country’s future. a) never b) once or twice a year a) the economy c) 3 to 5 times a year b) education d) 6 to 12 times a year c) integrity in government e) at least once a month d) national defense e) some other issue
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