In the field of psychometrics, the concept of reliability is used as a measure of consistency. To be more specific, reliability is defined as the repeatability or consistency of a measure. A measure is considered reliable if approximately the same results are obtained over time or across some other category, assuming the measure itself has not been amended or updated. There are multiple types of reliability. Inter-rater reliability measures the degree to which different raters give consistent estimates of the same phenomenon. Test-retest reliability is used to assess the consistency of a measure from one time period to another. Parallel reliability assesses the consistency of the results of two tests constructed in the same way from the same content domain. Internal consistency reliability assesses the consistency of results across items within an assessment.

 The 2021 Style Insights Reliability Study is an internal consistency reliability study and is part of TTI SI’s ongoing continuous improvement process.