Psychometric Considerations of the MMPI2

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Psychometric Considerations of the MMPI-2

• William P. Wattles, Ph.D.
• Francis Marion University

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• MMPI/MMPI-2 second most widely used test by
  clincical psychologists (86)
• Translated into more than 50 languages

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Original MMPI

• Published 1943
• Paper and pencil improvement on clinical
  interview and individual psychological testing

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Prior to MMPI Logical Keying

• Test items generated rationally based on
• Face validity
• Subjective judgment
• Logically keyed items problematic
• Subject to faking
• Not always correct

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Empirical Keying

• Original items came from many sources.
• Pool of 1,000 items reduced to 566
• Rewritten to be less formal and allow for some
  reversal of responses.

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Control Group

• 724 Visitors to the hospital in Minnesota.
• Representative of Minnesota in the 1930s
• 16-65
• Average age mind 30s
• Rural
• 8th grade education
• White

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Empirical Keying

• Using groups of diagnosed patients
• Contrast and Cross-validation

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MMPI vs MMPI 2

• Improved norms
• Score has meaning only when compared to a
  representative sample.
• Original sample Caucasian, 35, married, small
  town, good job.
• New sample large and more representative.
• Higher education level than population

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MMPI-2 normative group

• 2600 Participants
• Paid 15 (40 for couples)
• Tested in 7 locations
• Minnesota, Ohio, North Carolina, Washington,
  Pennsylvania, Virginia, California
• Selected from phone directories

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MMPI-2 composition

• 2600 Participants (started with 2900)
• 1138 men
• 1462 women
• Age 18-85 (M41, SD15)
• 61 married
• Education 3-20 years (M14, SD2)

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MMPI-2 Restandardization

• Caucasian 81
• African-American 12
• Hispanic 3
• Native-American 3
• Asian-American 1

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Requirements

• Eight Grade reading level required
• Satisfactory cooperation and commitment to task
• Internal checks for the above

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T Score transformations

• Transforming a score makes it easier to
  interpret.
• 13 validity and clinical scales converted to T
  scores
• T score is a standard score with a mean of 50 and
  a standard deviation of 10.
• Thus, a 70 is like a Z score of 2

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Standard Scores or Z scores

• Z score how many standard deviations a score
  lies above or below the mean.

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68
95
99.7
46
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Percent of scores falling below
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99.85
97.5
84
46
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Z-score
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MMPI-2 T score
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MMPI Uniform T score

• Original linear T-scores were problematic because
  the underlying data is somewhat skewed.

• Thus a T score on one scale represented a
  different percentile than one on another scale

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MMPI Uniform T-scores

• Involve averaging of the T-scores across the
  scales.

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Frequency high points in contemporary settings
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T-score cutoff

• Formerly T-scores of 70 were considered
  clinically significant. Now the MMPI-2 recommends
  65.
• That puts the score above 93 of those who answer
• 65-50/10 1.5
• 1.5 .9332 area under standard normal curve to
  the left of Z 1.5

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Intercorrelations

• There is considerable overlap between some
  scales. 13 of 39 items in scale 6 also appear in
  scale 8

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Homogeneity of items

• The empirical keying approach did not favor item
  homogeneity thus internal consistency is not
  high.

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Temporal Stability

• Ability, interest and aptitude tests should be
  high in temporal stability
• Personality and psychopathology measures less
  clear.

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Test-retest reliability one week
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Test-retest reliability

• Summary. Test is fairly stable and changes when
  current appear consistent. Significant changes
  generally correctly reflect behavior change.

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Factor Analysis

• Two strong factors identified
• General maladjustment and psychotic thought
• Neurotic characteristics

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Response sets and styles

• Charges that MMPI and MMPI-2 were confounded by
  response style.
• Block modified MMPI to have equal number of true
  and false items
• Test seems to be valid in a variety of settings.

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MMPI vs MMPI-2

• Validity similar
• Raw Scores higher on MMPI-2
• May be explained by instructions
• T-scores compensate for higher raw scores

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Items changed MMPI-2
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Basic Qualifications for users

• Graduate-level course in psychological testing.
• Standard scores
• Transformations
• Understand limits of accuracy
• Standard error of measurement

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Basic Qualifications for users

• Graduate-level course in psychopathology
• Personality structure
• Dynamics
• Deviance psychodiagnostic concepts
• Diagnostic systems
• Broad understanding of human personality

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Lexile Reading Levels in SIRS
Lexile Score Table from www.lexile.com

• What Are Lexile Reading Levels
• Lexile scores match reader ability and text
  difficulty, allowing individualized monitoring of
  student progress.
• Due to the accountability requirements of NCLB,
  many states are turning to standardized systems
  for reading which help to track student progress.
• How does it Work?
• Lexile measures are based on two well-established
  predictors of how difficult a text is to
  comprehend semantic difficulty (word frequency)
  and syntactic complexity (sentence length).

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Reading Level
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Lexile examples

• 39 I am an important person
• 294 I have not lived the right kind of life
• 603 I do not read every editorial in the
  newspaper everyday
• 860 Most anytime I would rather sit and daydream
  than do anything else.
• 1042 I am troubled by discomfort in the pit of my
  stomach every few days or oftener.

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Testing conditions

• Quiet room one setting preferred
• Okay to take over several intervals
• Person must have privacy and no help
• Simple definitions of words permitted along with
  rephrasing of colloquialisms
• Usually sufficient to say Just indicate the way
  you see it.

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• Examiner to act in a serious and professional
  manner
• Dont linger too long in one area

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The End
The End