Reliability & Validity Flashcards
What can high reliability guarantee?
Consistency
How can one test reliability?
Test-retest correlation
How does test-retest correlation work?
Administering an instrument twice to same population
How does one avoid the practice effect when doing test-retest?
Time difference must be long enough
But short enough so the underlying state does not change
Time difference for test-retest in psychiatric studies
2-14 days
What measures internal consistency of a test?
Cronbachs alpha
How does cronbachs alpha test internal consistency?
By correlating each item with the total score and averaging the correlation coefficient
Values of Cronbachs alpha
Negative infinity to 1
What Cronbachs alpha values make sense
Positive values only
Cut off for Cronbachs alpha for a test to be internally consistent?
0.7
What is split half reliability?
Splitting scale in two parts and examining the correlation
What is intraclass correlation coefficient used for?
Continuous variables
What is the intraclass correlation coefficient?
Proportion of total variables of measurement that reflects true between subject variability
Range of intraclass correlation coefficient?
0 (unreliable) - 1 (perfect reliability)
What can ICC be measured for?
Relative or absolute agreement
Difference between relative and absolute agreement
Relative ICC is always higher
Levels of ICC and their meanings
- 6 = fair
- 8 = very good
- 9 = excellent
What is ANOVA intraclass coefficient used for?
Quantitative data with more than 2 rates/groups
What is used to test relaibility for nominal data with more than 2 categories?
Kappa or weighted kappa
What is face validity?
Subjective measure of deciding whether a test measures the construct of interest at face value
Types of construct validity
Content Criterion Convergent Discriminant Experimental
What is criterion validity made up of
Concurrent
Predictive
What is construct validity?
Measures whether a test really measures the construct of interest
What is unified construct validity?
Both content and criterion validity