Assessing test-retest reliability involves measuring the same group of participants at two separate times and calculating the correlation between their scores. This statistical relationship is commonly visualized using a scatterplot. Since standard research designs often only test participants once, researchers might specifically design a two-phase study for a new measure to evaluate this reliability. Alternatively, data from a study designed to answer a different research question can be utilized if the measure was administered multiple times. For instance, if an instructor measures students' attitudes at the start and end of a semester to detect learning changes, the correlation between those two sets of scores can simultaneously be used to assess the measure's test-retest reliability, even if no overall attitude change occurred.