One of the most popular personality tests in the world is
the Myers-Briggs Type Indicator (MBTI), a psychological-assessment
system based on the work of psychologist Carl Jung. Two and a half
million Americans a year take the Myers-Briggs. Eighty-nine
companies out of the US Fortune 100 make use of it, for
recruitment and selection or to help employees understand
themselves or their co-workers.
The MBTI asks the candidate to answer a series of ‘forced-choice’
questions, where one choice identifies you as belonging to one of
four paired traits. The basic test takes twenty minutes, and at
the end you are presented with a precise, multi-dimensional
summary of your personality. The MBTI test classifies people into
types based on 4 bi-polar dimensions;
Extraversion-Introversion (E-I)
Distinguishes a preference for focusing attention on, and drawing
energy from, the outer world of people and things versus the inner
world of ideas and impressions.
Sensing-INtuition (S-N)
Distinguishes a preference for gathering data directly through the
senses as facts, details, and precedents (Sensing) versus
indirectly as relationships, patterns, and possibilities (INtuition).
Thinking-Feeling (T-F)
Distinguishes a preference for deciding via objective, impersonal
logic (Thinking) versus subjective, person-centered values
(Feeling).
Judging-Perceiving (J-P)
Distinguishes an outward preference for having things planned and
organized (Judging) versus a flexible style based more on staying
open to options than deciding (Perceiving).
The sixteen personality types resulting from the cross-products of
these four dimensions are illustrated below.
As you can see, there are 16 distinct personality types, so
someone may be classed as ESFP or INTJ, or some other combination.
This is obviously a different way of looking at personality from
the big 5 personality trait theory of Costa & McCrae.
Psychologists judge the worth of any personality test by two basic
criteria: validity and reliability. Validity indicates that a test
measures what it says it measures and reliability indicates that a
test delivers consistent results.
Validity of MBTI
The validity of a test estimates how well the test measures what
it purports to measure. There are two types of validity that
should be considered:
-
Construct validity - does the MBTI
relate to other scales measuring similar concepts?
-
Criterion-related validity - does the
MBTI predict specific outcomes related to interpersonal relations
or job performance?
The National Academy of Sciences committee reviewed data from
over 20 MBTI research studies and concluded that only the
Intraversion-Extroversion scale has adequate construct validity.
That is high correlations with comparable scales of other tests
and low correlations with tests designed to assess different
concepts. In contrast, the S-N and T-F scales show relatively weak
validity. No mention was made in this review about the J-P scale.
Overall, the review committee concluded that the MBTI has not
demonstrated adequate validity although its popularity and use has
been steadily increasing. The National Academy of Sciences review
committee concluded that: ‘at this time, there is not sufficient,
well-designed research to justify the use of the MBTI in career
counseling programs’, the very thing that it is most often used
for.
Reliability of MBTI
Reliability is the degree of consistency with which a test
measures what it is said to measure. Test length greatly affects
reliability with longer tests tending to be more reliable.
Reliability can be measured using reliability coefficients, and
for short personality tests these should be in the range 0.70 to
0.80. The MBTI reports reliability coefficients for its four
scales on general population samples in the ranges from 0.61 to
0.87.
The practical effect of this is that even though the MBTI
claims to reveal a subjects’ inborn, unchanging personality type,
as many as 75% of test takers are assigned a different type when
they take the Myers-Briggs a second time.
Academic psychologists and commercial test providers have a
tendency to put a different ‘spin’ on how valid and reliable these
personality questionnaires are, with the test providers
unsurprisingly ‘talking up’ both validity and reliability.
The following quotes are from David M. Boje, Ph.D., Professor of
Management in the Management Department, CBAE at New Mexico State
University (NMSU).
“…do not treat the archetype scores of M-B as anything more
than Astrology”
“The test is not valid or legal to use for personnel assignments,
hiring, or promotion. It does not have predictive validity for
such uses. It is a useful guide, and no more. Problem is, people
go to a workshop, get excited and treat M-B as a secret window
into the mind of their co-workers.”
Robert Spillane, Professor of Management at the Graduate School of
Management at Macquarie University argues that research shows that
efforts to predict performance from personality and motivation
tests have been consistently and spectacularly unsuccessful.
"[Tests] trivialize human behavior by assuming that (fake)
attitudes predict performance. Not only is this incorrect but
testers offer no explanations for behavior beyond the circular
proposition that behavior is caused by traits which are inferred
from behavior,".
"The technical deficiencies of most personality tests have been
known for many years. Yet they are conveniently ignored by those
with vested interests in their continued use,"
You can easily find hundreds of quotes like these, in which noted
and published psychologists call into question the use of
personality tests. However, judging from the number of and
increase in personality tests used, they are likely to be part of
the selection process for the foreseeable future. As someone
taking one of these tests you just have to hope that the HR
professionals who have selected the test have realistic
expectations of validity and reliability and have been trained to
interpret the results properly.
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