Rule-Out and Rule-In scales for the M test for malingering: a cross-validation

Area of Science:

• Psychological assessment
• Forensic psychology
• Clinical psychology

Background:

• The M test has historically shown limited effectiveness in detecting malingering.
• Rogers et al. introduced revised scoring scales (Rule-In and Rule-Out) to enhance malingering detection.
• Initial findings suggested high accuracy rates for these new scales.

Purpose of the Study:

• To cross-validate the efficacy of the Rule-In and Rule-Out scales for malingering assessment.
• To evaluate the classification accuracy of the proposed decision rules in a new sample.

Main Methods:

• Cross-validation of the decision rules proposed by Rogers et al.
• Analysis of classification accuracy using the most conservative decision rule.
• Calculation of malingerer detection rates and false positive rates.

Main Results:

• The cross-validation yielded lower classification accuracy than initially reported.
• The most conservative decision rule identified only 72.7% of malingerers.
• A high false positive rate of 50.8% was observed with this conservative rule.

Conclusions:

• The revised M test scales demonstrate reduced utility for screening malingering upon cross-validation.
• The high false positive rate limits the practical application of the conservative decision rule.
• Further research is needed to refine malingering detection methods in psychological assessment.