Validity and Reliability THESIS
Validity u Construct Validity u Content Validity u Criterion-related Validity u Face Validity
Construct Validity Is the underlying construct or theoretical foundation of the survey consistent with research and information on the topic?
Content Validity Does the content of the items in the instrument accurately reflect the underlying construct?
Criterion-related Validity Does the instrument contain the proper criteria for measuring the traits or constructs of interest?
Face Validity Does the instrument look like it will measure what it is supposed to measure?
Reliability u Test - Retest u Alternative forms u Split halves u Internal consistency
Test - Retest Method u Administer instrument u Analyze responses u Administer instrument again under exact conditions u Correlate responses
Alternative Forms Method u Administer instrument u Analyze responses u Administer different form of same survey u Correlate responses
Split Halves Method u Administer instrument u Separate responses by odd and even items u Correlate two halves u Correct using Spearman-Brown
Internal Consistency (Cronbach’s Alpha) u Administer instrument u Compute inter-item correlation matrix u Compute mean inter-item correlation u Enter alpha formula
Question Can a survey be: Valid but not reliable? Reliable but not valid?