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8-2McGraw-Hill/Irwin © 2003 The McGraw-Hill Companies, Inc.,All Rights

Reserved.

Part TwoTHE DESIGN OF RESEARCH

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Chapter EightMEASUREMENT

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Measurement

• Selecting observable empirical events

• Using numbers or symbols to represent aspects of the events

• Applying a mapping rule to connect the observation to the symbol

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What is Measured?

• Objects: – Things of ordinary experience – Some things not concrete

• Properties: characteristics of objects

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Characteristics of Data

• Classification

• Order

• Distance (interval between numbers)

• Origin of number series

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Data Types

Order Interval OriginNominal none none none

Ordinal yes unequal none

Interval yes equal or none

unequal

Ratio yes equal zero

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Sources of Measurement Differences

• Respondent

• Situational factors

• Measurer or researcher

• Data collection instrument

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Validity

• Content Validity

• Criterion-Related Validity– Predictive– Concurrent

• Construct Validity

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Reliability

• Stability– Test-retest

Equivalence– Parallel forms

• Internal Consistency– Split-half– KR20– Cronbach’s alpha

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Practicality

• Economy

• Convenience

• Interpretability