Internal consistency measures whether items on a test that aim to measure the same construct produce similar scores, and is typically measured by Cronbach's alpha, which ranges from negative infinity to one. Construct validity refers to how well a test measures the intended, underlying concept, while test-retest reliability evaluates a test's stability over time by administering it twice to a group and correlating their scores. Discriminative ability reflects a test's power to discriminate between different subjects or conditions.

1. Internal consistency
• In statistics and research, internal consistency is typically a measure
based on the correlations between different items on the same test
(or the same subscale on a larger test). It measures whether several
items that propose to measure the same general construct produce
similar scores.
• Internal consistency is usually measured with Cronbach's alpha, a
statistic calculated from the pairwise correlations between items.
• ranges between negative infinity and one.

3. Construct validity
• Construct validity is the appropriateness of inferences made on the
basis of observations or measurements (often test scores), specifically
whether a test can reasonably be considered to reflect the
intended construct
• Construct validity concerns how well a set of indicators represent or
reflect a concept that is not directly measurable

4. Test-retest reliability
• Test-retest reliability is a measure of reliability obtained by
administering the same test twice over a period of time to a group of
individuals. The scores from Time 1 and Time 2 can then be
correlated in order to evaluate the test for stability over time

5. Discriminative ability
• Discriminative ability reflects the ability of an instrument/method to
discriminate between different things
• Can be assessed by calculating sensitivity, specificity, positive and
negative likelihood ratios, ROC curves