What methods would test reliability across time? (Reliability Methods)
- Test re-test
- Alternative forms
What methods would test internal consistency of reliability? (Reliability Methods)
- Split half method
- Cronbach alpha
- Interrater reliability
What is test re-test? (Reliability Methods)
The degree to which an instrument measures the same way each time, in the same conditions, with the same P’s
How is test re-test calculated? (Reliability Methods)
- Administer scale to the same P’s at two separate times
- Compute the correlations between each scores
What is alternative forms? (Reliability Methods)
Changing the wording of questions in an equivalent form
How is alternative forms calculated? (Reliability Methods)
- Changing the order of the questions across two separate times
- Calculate correlations between the two scores
What is split half method? (Reliability Methods)
Group questions in the questionnaire that measure the same construct
How is the split half method calculated? (Reliability Methods)
Calculate the correlations between grouped items
What is Cronbach alpha? (Reliability Methods)
Splits the questions in every possible way and computes the correlation values for all splits (should be > .7)
What is the item reliability index? (Reliability Methods)
Correlations between scores of the item and scores on the scale as a whole x SD of item
In SPSS, what is needed for item reliability index? (Reliability Methods)
- Corrected item-total correlation
- Should be significant for all items
- If < .3, then remove item
What should be done on scales with only 2 items? (Reliability Methods)
- Compute bivariate persons correlation
- Reports P and R values as usual
