Editing Survey methodology (section)

===Reliability and validity of self-report measures===
Reliable measures of self-report are defined by their consistency.<ref name="Shaughnessy2011"/> Thus, a reliable self-report measure produces consistent results every time it is executed.<ref name="Shaughnessy2011"/> A test's reliability can be measured a few ways.<ref name="Shaughnessy2011"/> First, one can calculate a test-retest reliability.<ref name="Shaughnessy2011"/> A test-retest reliability entails conducting the same questionnaire to a large sample at two different times.<ref name="Shaughnessy2011"/> For the questionnaire to be considered reliable, people in the sample do not have to score identically on each test, but rather their position in the score distribution should be similar for both the test and the retest.<ref name="Shaughnessy2011"/> Self-report measures will generally be more reliable when they have many items measuring a construct.<ref name="Shaughnessy2011"/> Furthermore, measurements will be more reliable when the factor being measured has greater variability among the individuals in the sample that are being tested.<ref name="Shaughnessy2011"/> Finally, there will be greater reliability when instructions for the completion of the questionnaire are clear and when there are limited distractions in the testing environment.<ref name="Shaughnessy2011"/> Contrastingly, a questionnaire is valid if what it measures is what it had originally planned to measure.<ref name="Shaughnessy2011"/> Construct validity of a measure is the degree to which it measures the theoretical construct that it was originally supposed to measure.<ref name="Shaughnessy2011"/>