MMPI-2 profile code types and measurement error

Area of Science:

• Psychological assessment
• Psychometrics

Background:

• The Minnesota Multiphasic Personality Inventory-2 (MMPI-2) is a widely used psychological assessment tool.
• Code types derived from MMPI-2 profiles are crucial for interpretation, but their stability under measurement error is not fully understood.

Purpose of the Study:

• To investigate the stability and potential change in MMPI-2 code types due to measurement error.
• To determine how different levels of T-score profile definition influence code type stability.

Main Methods:

• Simulated MMPI-2 profiles were generated for 12 well-defined code types across 9 T-score definition levels.
• Simulations incorporated measurement error based on normative and clinical group data.
• Frequencies and percentages of profiles retaining the original code type were calculated.

Main Results:

• Code type stability generally increased with higher T-score profile definition levels.
• For instance, stability rose from 27-37% at 3-point definition to over 90% for definitions exceeding 15 points.
• Simulations using clinical group data also showed increased stability with greater definition.

Conclusions:

• MMPI-2 code type stability is significantly influenced by the precision of the T-score profile definition.
• Higher levels of profile definition enhance the reliability of MMPI-2 code type interpretation.
• These findings have implications for the accurate interpretation of MMPI-2 results in clinical and research settings.