1. Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Chapter 16: Measurement in Experimental- Type Research Action process of gathering information to answer research questions or queries

2. 2 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Measurement: The Foundation of Experimental-Type Design

3. 3 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. What is measurement? The translation of observations into numerical values or numbers.

4. 4 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. What are the 3 Steps in Measurement? Conceptual work by the researcher to identify and define what must be measured Developing an operational definition of the concept Ensure Reliability and validity

5. 5 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. On the basis of the definition of the concept, specific indicators (scales, questionnaires, rating forms) are developed To develop an indicator it is necessary to specify the numerical level at which the variable will be measured There are 4 levels of measurement: Nominal, ordinal, interval and ratio

6. 6 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Levels of Measurement  Nominal  Ordinal  Interval  Ratio

7. 7 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Nominal  Simplest classification  Puts into mutually exclusive categories or labels

8. 8 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Ordinal  Ranking  Uses a hierarchy  Intervals between numbers are not equivalent

9. 9 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Interval  Equivalent distance between numbers  Allows for mathematical manipulation

10. 10 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Ratio  Similar to interval but also has absolute zero point

11. 11 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Instrumentation Thinking and Action  Lexically define your construct from the literature  Select an existing instrument that measures it or develop one in the absence of adequate instrumentation

12. 12 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Steps in Developing Instrumentation  Lexically define construct with specificity and clarity  Formulate items that test the entire construct  Eliminate items for parsimony and rigor  Decide on a measurement scheme to answer your research questions  Test the rigor of the instrument

13. 13 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. What are Scales? Scales are tools for the quantitative measurement of the degree to which individuals possess a specific attribute or trait 3 Types: Likert-type Guttman Semantic Differential

14. 14 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Examples of Measurement Schemes  Likert-type scale: items that reflect an underlying construct, worded positively or negatively  Guttman scale: unidimensional (cumulative), hierarchically arranged, some items are arranged so that endorsement of one item means endorsement of the items below it  Semantic differential: “bipolar” rating scale, usually to assess attitudes and beliefs

15. 15 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. This is taken from Wikimedia Commons, accessed on 9/26/13

16. 16 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Figure 1. Examples of Likert-Scaled Survey Items http://jan.ucc.nau.edu/~mid/edr72 0/class/survey/responses/reading4 -2-1.htmlhttp://jan.ucc.nau.edu/~mid/edr72 0/class/survey/responses/reading4 -2-1.html, accessed 9/26/13 Example Guttman Scale

17. 17 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Semantic differential The semantic differential is a scale used for measuring the meaning of things and concepts. There are two aspects of meaning: denotative and connotative. The semantic differential measures connotative meaning. Creating the scale The scale is set up using polar adjectives (opposite-meaning terms) at each end. After examining the connotative meaning of thousands of concepts, Charles Osgood and his associates identified three major dimensions of meaning: strength, value, and activity. The first two examples below fit the theme of strength. The second two represent value, and the last two illustrate activity. The respondent is asked to rate an object, person or any concept, by putting a mark on one of the 7 spaces along each dimension. http://psychology.ucdavis.edu/sommerb/sommerdemo/scaling/semdiff.htmhttp://psychology.ucdavis.edu/sommerb/sommerdemo/scaling/semdiff.htm, accessed 9/26/13

18. 18 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Denotation - what a name or concept refers to (denote - to mark out plainly, to indicate) Connotation - the suggestive significance of a word, apart from its explicit and recognized meaning Consider automobiles or school mascots. Names such as "Jaguar" or "Huskies" denote animals. Their connotation is power. In contrast, the "Oregon Ducks" project a different image or connotative meaning. denotation = eagle, bird connotation = strength, power Strong ____:____:____:____:____:__ __:____ Weak Decisiv e ____:____:____:____:____:__ __:____ Indecisive Good ____:____:____:____:____:__ __:____ Bad Cheap ____:____:____:____:____:__ __:____ Expensive Active ____:____:____:____:____:__ __:____ Passive Lazy ____:____:____:____:____:__ __:____ Industrious Semantic differential The semantic differential is a scale used for measuring the meaning of things and concepts. There are two aspects of meaning: denotative and connotative. The semantic differential measures connotative meaning. Creating the scale The scale is set up using polar adjectives (opposite-meaning terms) at each end. After examining the connotative meaning of thousands of concepts, Charles Osgood and his associates identified three major dimensions of meaning: strength, value, and activity. The first two examples below fit the theme of strength. The second two represent value, and the last two illustrate activity. The respondent is asked to rate an object, person or any concept, by putting a mark on one of the 7 spaces along each dimension.

19. 19 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Stro ng ____:____:____:____: ____:____:____ Weak Dec isiv e ____:____:____:____: ____:____:____ Indecisiv e Go od ____:____:____:____: ____:____:____ Bad Che ap ____:____:____:____: ____:____:____ Expensiv e Acti ve ____:____:____:____: ____:____:____ Passive Laz y ____:____:____:____: ____:____:____ Industrio us http://psychology.ucdavis.edu/sommerb/sommerdemo/scaling/sem diff.htmhttp://psychology.ucdavis.edu/sommerb/sommerdemo/scaling/sem diff.htm, accessed 9/26/13

20. 20 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Confidence in Instruments In selecting a scale or other type of measurement, the researcher is concerned with 2 issues: 1.Whether the instrument consistently or reliably measures a variable 2.Whether the instrument represents an adequate or valid measure of the underlying concept of interest

21. 21 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Confidence in Instruments Reliability Stability Tests of internal consistency Equivalence Validity

22. 22 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. What Is Reliability?  Reliability is concerned with stability or how consistently the instrument measures the lexically defined concept of interest.

23. 23 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. What Is Instrument Validity?  The extent to which an instrument reflects the concept being examined  The extent to which an instrument measures its lexically defined concept

24. 24 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Considerations in Selecting a Measure Purpose of assessment Psychometric properties Population

25. 25 Copyright © 2011, 2005, 1998, 1993 by Mosby, Inc., an affiliate of Elsevier Inc. Informaton Sources Self-report Proxy Direct observation Chart extraction