Test results can’t be valid if they aren’t reliable. If your instruments for collecting data don’t produce reliable results, you can’t draw any conclusions. If your results are skewed, then your conclusion is likely to be as well. Validity is essential in all types of testing. If a measurement is consistent, then it’s reliable. If a measurement is accurate, then it’s valid. Ideally, you want your equipment to be both reliable and valid – or consistent and accurate – be it a thermometer, questionnaire, or scale. Validity is all about accuracy in your measurements, while reliability determines consistency. Both are used to determine how well a test measures something, but the two of them tell you different things about your test. The difference between validity and reliability is important in research, testing, and statistical analysis.
