Reliability of the MMPI-2 Subtle and Obvious scales with psychiatric inpatients

Area of Science:

• Psychological assessment
• Clinical psychology
• Psychometric evaluation

Background:

• The Minnesota Multiphasic Personality Inventory-2 (MMPI-2) is a widely used psychological assessment tool.
• The Subtle and Obvious scales are components of the MMPI-2 designed to enhance interpretation.
• Reliability is a critical measure of assessment tool consistency.

Purpose of the Study:

• To determine the internal consistency reliability of the Subtle and Obvious scales of the MMPI-2.
• To assess the impact of Subtle scale items on the reliability of the full MMPI-2 clinical scales.
• To evaluate the psychometric properties of MMPI-2 scales in a psychiatric inpatient population.

Main Methods:

• Internal consistency reliability was estimated using Cronbach's alpha for the Subtle and Obvious scales.
• Analyses were conducted on data from a group of psychiatric inpatients.
• Reliability was re-evaluated after removing the Subtle scale items from the full clinical scales.

Main Results:

• Most Subtle scales demonstrated unacceptably low internal consistency reliability (ranging from .32 to .59), with the exception of Subtle Scale 3 (Hy).
• The inclusion of Subtle items attenuated the reliability of the corresponding full MMPI-2 clinical scales.
• Removing the Subtle items resulted in comparable and acceptable reliabilities across all MMPI-2 scales (ranging from .75 to .92).

Conclusions:

• The Subtle scales of the MMPI-2 exhibit poor internal consistency reliability in psychiatric inpatients.
• The findings suggest that the Subtle items may negatively impact the reliability of the full MMPI-2 clinical scales.
• It is hypothesized that the low reliability of the Subtle scales may attenuate the validity of the full MMPI-2 clinical scales.