# aberrance

The *aberrance* package contains a collection of functions for detecting several types of aberrant behavior, including:

**Answer copying**, using statistics such as the \(\omega\) statistic (Wollack, 1997).
**Answer similarity**, using statistics such as the \(GBT\) statistic (van der Linden & Sotaridona, 2006) and the \(M4\) statistic (Maynes, 2014).
**Nonparametric misfit**, using statistics such as the \(ZU3\) statistic (van der Flier, 1982) and the \(H^T\) statistic (Sijtsma, 1986).
**Parametric misfit**, using statistics such as the standardized log-likelihood statistic (Drasgow et al., 1985) and its various corrections (Bedrick, 1997; Gorney et al., 2024; Molenaar & Hoijtink, 1990; Snijders, 2001).
**Preknowledge**, using statistics such as the signed likelihood ratio test statistic (Sinharay, 2017).
**Rapid guessing**, using methods such as the custom threshold method (Wise et al., 2004; Wise & Kong, 2005), the normative threshold method (Wise & Ma, 2012), and the cumulative proportion correct method (Guo et al., 2016).
**Test tampering**, using statistics such as the erasure detection index (Wollack et al., 2015; Wollack & Eckerly, 2017) and its corrected versions (Sinharay, 2018).

## Installation

Install the released version from CRAN:

Alternatively, install the development version from GitHub: