Psychometric Considerations
of the MMPI-2
William P. Wattles, Ph.D.
Francis Marion University
• MMPI/MMPI-2 second most widely used
test by clincical psychologists (86%)
• Translated into more than 50 languages
Original MMPI
• Published 1943
• Paper and pencil
improvement on
clinical interview and
individual
psychological testing
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
Face Validity
• Does the test appear to measure what it is
purported to Measure?
Face Validity
0 I do not feel sad.
1 I feel sad.
2 I am sad all the time and can't snap out of it.
3 I am so sad or unhappy that I can't stand it.
• 70. I am easily downed in an argument
• 89 My hardest values are with myself
• 267 I have periods in which I feel unusually
cheerful without any special reason.
• 219 I have been disappointed in love
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.
Control Group
• 724 Visitors to the hospital in Minnesota.
• Representative of Minnesota in the 1930s
–
–
–
–
–
16-65
Average age mind 30’s
Rural
8th grade education
White
Empirical Keying
• Using groups of diagnosed patients
• Contrast and Cross-validation
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
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
MMPI-2 composition
• 2600 Participants (started with 2900)
– 1138 men
– 1462 women
• Age 18-85 (M=41, SD=15)
• 61% married
• Education 3-20 years (M=14, SD=2)
MMPI-2 Restandardization
•
•
•
•
•
Caucasian 81%
African-American 12%
Hispanic 3%
Native-American 3%
Asian-American 1%
Requirements
• Eight Grade reading level required
• Satisfactory cooperation and commitment to
task
• Internal checks for the above
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
Standard Scores or Z scores
• Z score: how many standard deviations a
score lies above or below the mean.
68%
95%
99.7%
46
Percent of scores falling below
Z score
3
2
1
-1
-2
-3
% below
99.9%
97.5%
84.0%
16.0%
2.5%
0.1%
% within
99.7%
95.0%
68.0%
99.85%
97.5%
84%
46
Z-score
z
x

33
MMPI-2 T score
t  50  10(
x

)
33
MMPI Uniform T score
• Original linear Tscores 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
MMPI Uniform T-scores
• Involve averaging of
the T-scores across the
scales.
Frequency high points in
contemporary settings
Scale
1
2
3
4
6
7
8
9
Males
Females
linearT
uniform T linearT
uniform T
5.2
4.7
6.3
4.2
21.6
13.8
15.7
15.7
3.4
3.9
3.7
6.3
10.3
12.9
11.5
13.6
18.5
18.5
23.6
28.3
4.7
8.6
2.6
3.1
29.3
29.3
29.8
19.9
6.9
8.2
6.8
8.9
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
Intercorrelations
• There is considerable overlap between some
scales. 13 of 39 items in scale 6 also appear
in scale 8
Homogeneity of items
• The empirical keying approach did not
favor item homogeneity thus internal
consistency is not high.
Temporal Stability
• Ability, interest and aptitude tests should be
high in temporal stability
• Personality and psychopathology measures
less clear.
Test-retest reliability one week
Scale
L
F
K
1
2
3
4
5
6
7
8
9
0
Males (82) Females
0.77
0.78
0.84
0.85
0.75
0.72
0.81
0.82
0.67
0.89
0.87
0.83
0.92
(111)
0.81
0.69
0.81
0.85
0.77
0.76
0.79
0.73
0.58
0.88
0.8
0.68
0.91
Test-retest reliability
• Summary. Test is fairly stable and changes
when current appear consistent. Significant
changes generally correctly reflect behavior
change.
Internal consistency
• Moderate, not a strength for the MMPI-2
due to empirical keying approach.
Factor Analysis
• Two strong factors identified
– General maladjustment and psychotic thought
– Neurotic characteristics
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.
MMPI vs MMPI-2
• Validity similar
• Raw Scores higher on MMPI-2
– May be explained by instructions
• T-scores compensate for higher raw scores
Items changed MMPI-2
Basic Qualifications for users
• Graduate-level course in psychological
testing.
–
–
–
–
Standard scores
Transformations
Understand limits of accuracy
Standard error of measurement
Basic Qualifications for users
• Graduate-level course in psychopathology
–
–
–
–
–
Personality structure
Dynamics
Deviance psychodiagnostic concepts
Diagnostic systems
Broad understanding of human personality
Lexile Reading Levels in
SIRS
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 wellestablished predictors of how difficult a
text is to comprehend: semantic difficulty
(word frequency) and syntactic complexity
(sentence length).
Lexile Score Table from www.lexile.com:
Age
Schoo
l Year
Typical Lexile
Level
7
3
300- 800
8
4
400- 900
9
5
500-1000
10
6
600-1100
11
7
700-1200
12
8
800-1300
13
9
900-1400
14
10
1000-1700
15
11
1100-1700
16
12
1200-1700
Reading Level
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.
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.”
• Examiner to act in a serious and
professional manner
• Don’t linger too long in one area
The End
The End