Measuring my intelligence by means of asking my mum. The measurement of my weight by means of a bathroom scale is very reliable: if I step on and off the scales over and over again, it’ll keep giving me the same answer. Experts(in this case, math teachers), would have to evaluate the content validity by comparing the test to the learning objectives. Reliability is actually a very simple concept: it refers to the repeatability or consistency of your measurement. of each question, analyzing whether each one covers the aspects that the test was designed to cover.Ī 4th grade math test would have high content validity if it covered all the skills taught in that grade. Assessing content validity is more systematic and relies on expert evaluation. Studies most frequently assessed the validity (criterion and convergent) ( n 65), face and content validity ( n 2), test-retest reliability ( n 10) and intra-instrument reliability ( n 1) of the measurement tools. On the other hand, content validity evaluates how well a test represents all the aspects of a topic. When a test has strong face validity, anyone would agree that the test’s questions appear to measure what they are intended to measure.įor example, looking at a 4th grade math test consisting of problems in which students have to add and multiply, most people would agree that it has strong face validity (i.e., it looks like a math test).

The difference is that face validity is subjective, and assesses content at surface level. In order for any scientific instrument to provide measurements that can be trusted, it must be both reliable and valid. Face validity and content validity are similar in that they both evaluate how suitable the content of a test is.

Reliability and validity of measurement