Chapter Five

Measurement Concepts

Terms

• Reliability

• True Score

• Measurement Error

How Can we assess Reliability

• Test-Retest Reliability• Internal Consistency Reliability

– Split half reliability– Cronbach’s alpha

• Inter-rater reliability

Reliability vs. Validity

• Reliability-consistency of the measure• Validity-truth---does the study measure

what it says it will measure…is it valid

• ****A measure can be reliable and not valid, but it canno be valid unless it is reliable.

• Construct validity the adequacy of the operational definitions of variables

• Criterion-Oriented Validity- examining the relationship between scores on a measure and some criterion.

Indicators of Validity

• Face validity tells whether the measure appears to measure what it is suppose to..

• Four types of Criterion-related research approaches

Types of Criterion-oriented research

approaches

• Predictive Validity • Concurrent Validity • Convergent Validity • Discriminant Validity

• Predictor Validity- research measuring the extent to which the measure allows you to predict future behaviors. (SAT)

• Concurrent Validity-examines the relationship between the measure and a criterion at the same time.– research whether two or more groups of people differ on a

measure in expected ways. • Convergent validity when a measure relates to other

scores of the same or similar constructs in a meaningful and predicted way.– Shy Q scores and Fear of Negative Evaluation Scale

• Discriminant validity the measure should discriminate between the construct being measured and other non-related constructs.– Shy Q and Zuckerman’s Sensation seeking Scale.

Variables & Measurement Scales• Nominal scales have no numerical or quantitative

properties, they are naming scales, and their only property is identity .

• Ordinal scales tell us about the relative order of magnitude, but they do not give us info about the differences b/t categories or ranks.

• Interval scale the measurement conveys info about the order and the distance b/t the values

• Ratio scales have all the properties of the previous scales and a true zero point that indicates the absence of the variable being measured