A confounding variable is an extraneous variable that is statistically related to or correlated with the independent variable. This means that as the independent variable changes, the confounding variable changes along with it. Failing to take a confounding variable into account can lead to a false conclusion that the dependent variables are in a causal relationship with the independent variable. Take, for example, a hypothetical study that found that people who carry a lighter in their pocket tend to have higher rates of cancer. Instead, there is a confounding variable of smoking; people who carry a lighter in their pocket are more likely to be smokers, and those who smoke are more likely to be diagnosed with cancer.
Construct validity is "the degree to which a test measures what it claims, or purports, to be measuring. Construct validity is the appropriateness of inferences made on the basis of observations or measurements often test scores , specifically whether a test measures the intended construct. Constructs are abstractions that are deliberately created by researchers in order to conceptualize the latent variable , which is correlated with scores on a given measure although it is not directly observable. Construct validity examines the question: Does the measure behave like the theory says a measure of that construct should behave? Construct validity is essential to the perceived overall validity of the test. Construct validity is particularly important in the social sciences , psychology , psychometrics and language studies. Psychologists such as Samuel Messick have pushed for a unified view of construct validity "
Reliability is the degree to which an assessment tool produces stable and consistent results. The obtained correlation coefficient would indicate the stability of the scores. Inter-rater reliability is especially useful when judgments can be considered relatively subjective.
Construct validity refers to the degree to which inferences can legitimately be made from the operationalizations in your study to the theoretical constructs on which those operationalizations were based. Like external validity , construct validity is related to generalizing. But, where external validity involves generalizing from your study context to other people, places or times, construct validity involves generalizing from your program or measures to the concept of your program or measures. I would like to tell two major stories here.