1. MEASUREMENT Research Methods University of Massachusetts at Boston ©2011 William Holmes 1

2. WHAT IS MEASUREMENT? Connecting variables with empirical data Assessment of presence of characteristic (classification) Assessment of how much of a characteristic is present (amount) 2

3. BASIS OF MEASUREMENT Definition of variables Clarity of definitions Examples of variables Procedures for classification or assessing amount of a characteristic 3

4. WAYS OF DEFINING VARIABLES Written definitions (Nominal) Examples (Epistemic) Theoretical (Nomothetic) Procedural (Operational) 4

5. HOW TO CLARIFY DEFINITIONS Focus your definition. Have it refer to only one thing. Identify what it is not. Give examples Provide some framework for variable 5

6. PROCEDURES FOR MEASUREMENT Decide whether you want to measure the presence of something, different types of something, or amounts of something Decide on the Level of Measurement Be sure categories are exhaustive, exclusive, and unidimensional 6

7. MEASURE PRESENCE WHEN The variable only refers to presence or absence of a single characteristic, or The variable refers to a dichotomy of characteristics, or The variable provides categories 7

8. MEASURE TYPES WHEN The variable refers to a classification, or The variable refers to a discrete list, or The variable refers to categories of something, or The variable is a typology 8

9. MEASURE AMOUNT WHEN The variable counts something, or The variable refers to a length of time, or The variable refers to the amount of something, or The variable refers to the degree of something 9

10. LEVELS OF MEASUREMENT Nominal/Categorical—presence of characteristics Ordinal—ranks of characteristics Interval—equal distance between ranks Ratio—equal distance and meaningful zero point 10

11. ASSESING RELIABILITY Test-Retest Procedure Split Halves Procedure Inter-Item Correlation Procedure Inter-Rater Procedure 11

12. ASSESSING VALIDITY Face Validity Method Construct Method Criterion Method Predictive Method 12

13. RECOGNIZING GOOD MEASURES: 1 Categories are exclusive, don’t overlap Categories are exhaustive, cover all possibilities Categories are unidimensional, refer to only one thing 13

14. RECOGNIZING GOOD MEASURES: 2 Categories are clear, easy to understand Evidence of reliability is offered Evidence of validity is offered 14