What two properties are typically assessed to ensure a measurement tool is appropriate for psychological research?

• A. Reliability and validity.
• B. Cost and speed.
• C. Ease of administration and popularity.
• D. Sample size and power.

Answer: (A)

The main idea is that a measurement tool must be reliable and valid to be appropriate for psychological research. Reliability means the tool yields consistent results across time, across items, or across raters, so you’re not fitting noise or random error into your data. For example, a test-retest reliability check shows scores stay similar when the same person takes the test again, internal consistency shows the items hang together well, and inter-rater reliability shows different scorers agree. Validity, on the other hand, is about accuracy: does the instrument actually measure the intended construct? Content validity ensures the items cover the full domain of the concept; construct validity looks at how the measure relates to other variables as theory predicts (convergent and discriminant validity); criterion-related validity checks how well the measure predicts or correlates with an external standard, either now or in the future. It's important to note that reliability is a prerequisite for validity—an instrument cannot be valid if it isn’t reliable, and you can have a reliable tool that isn’t measuring the right thing.

Costs, speed, ease of administration, and popularity affect practicality and feasibility, while sample size and statistical power influence the study design and the ability to detect effects. But these factors don’t determine whether the measurement tool actually measures the intended construct with accuracy and consistency.