Chapter 3 Notes (Part 2)

# Chapter 3 Notes (Part 2) - Chapter 3 part 2 The Measurement...

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1 Chapter 3 part 2 The Measurement of Behavior Continued Review s Types of measures b Observational, physiological, self-report s Scales of measurement b Nominal, ordinal, interval, and ratio s Reliability b Consistency or dependability of measure b Reliability = (true score variance) / (measurement error) Reliability s Reliability coefficient = 0 b The scores are nothing but measurement error s Reliability coefficient =1 b If all the total variance were true-score variance s Measure is reliable at .70

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2 Reliability s We can never know a person’s true score b We can estimate the reliability of our measure by analyzing the amount of variability in a set of scores: s Total variance = Variance due to true scores + variance due to measurement error s The portion due to true scores can be thought of as Systematic Variance Reliability (cont’d) s The reliability of a measurement technique is estimated or assessed by the proportion of the total variance in a data set that is due to true-score (i.e. systematic) variance vs. measurement error: s Reliability = True-score variance/ Total variance Reliability (cont’d) s Three basic methods of estimating the reliability of a measure: 1) Test-retest reliability 2) Interitem reliability 3) Interrater reliability Most estimates of reliability are obtained by examining the correlation between what are supposed to be two measures of the same behavior, attribute, or event
3 A Quick Primer in Correlation s A correlation coefficient is a statistic that expresses the strength of a relationship between two things b in this case two measures of the same behavior s Correlation coefficients range from

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## This note was uploaded on 04/14/2008 for the course PSYC 2094 taught by Professor Trcunningham during the Spring '07 term at Virginia Tech.

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Chapter 3 Notes (Part 2) - Chapter 3 part 2 The Measurement...

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