MEASUREMENT Research Methods University of Massachusetts at Boston

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

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

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

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

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

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

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

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

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

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

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

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

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