Thus, the correlation is positive. A negative relationship occurs when one variable goes up and the other goes down. For example, cigarette smoking and life expectancy-the more cigarettes you smoke, the shorter your life expectancy. The most important thing to remember is that correlations do not prove causation. Addressing causality requires other types of tests.
Reliability measures the consistency of responses.
The extent to which someone would answer the same survey with the same answers if taken again would be an example of test-retest reliability. This reliability information is calculated from a survey's internal consistency. We expect people to answer similar items similarly. The extent to which they do is a measure of the survey's internal consistency. Validity measures the appropriateness of inferences for a test.