MBTI :: Format and administration

The current North American English version of the MBTI Step I includes 93 forced-choice questions (there are 88 in the European English version).

Forced-choice means that the individual has to choose only one of two possible answers to each question. The choices are a mixture of word pairs and short statements.

Choices are not literal opposites but chosen to reflect opposite preferences on the same dichotomy. Participants may skip questions if they feel they are unable to choose.


Using psychometric techniques, such as item response theory, the MBTI will then be scored and will attempt to identify the preference, and clarity of preference, in each dichotomy.

After taking the MBTI, participants are usually asked to complete a Best Fit exercise (see below) and then given a readout of their Reported Type, which will usually include a bar graph and number to show how clear they were about each preference when they completed the questionnaire.


During the early development of the MBTI thousands of items were used.

Most were eventually discarded because they did not have high midpoint discrimination, meaning the results of that one item did not, on average, move an individual score away from the midpoint.

Using only items with high midpoint discrimination allows the MBTI to have fewer items on it but still provide as much statistical information as other instruments with many more items with lower midpoint discrimination.

The MBTI requires five points one way or another to indicate a clear preference.

 

Additional formats

Isabel Myers had noted that people of any given type shared differences as well as similarities. At the time of her death, she was developing a more in-depth method of measuring how people express and experience their individual type pattern.


In 1987, an advanced scoring system was developed for the MBTI.

From this was developed the Type Differentiation Indicator (TDI) (Saunders, 1989) which is a scoring system for the longer MBTI, Form J, which includes the 290 items written by Myers that had survived her previous item analyses.

It yields 20 subscales (five under each of the four dichotomous preference scales), plus seven additional subscales for a new Comfort-Discomfort factor (which purportedly corresponds to the missing factor of Neuroticism).


This factor's scales indicate a sense of overall comfort and confidence versus discomfort and anxiety: guarded-optimistic, defiant-compliant, carefree-worried, decisive-ambivalent, intrepid-inhibited, leader-follower, and proactive-distractible.

Also included is a composite of these called "strain."

Each of these comfort-discomfort subscales also loads onto one of the four type dimensions, for example, proactive-distractible is also a judging-perceiving subscale.

There are also scales for type-scale consistency and comfort-scale consistency.

Reliability of 23 of the 27 TDI subscales is greater than 0.50, "an acceptable result given the brevity of the subscales" (Saunders, 1989).


In 1989, a scoring system was developed for only the 20 subscales for the original four dichotomies.

This was initially known as Form K, or the Expanded Analysis Report (EAR).This tool is now called the MBTI Step II.


Form J or the TDI became known as Step III.

It was developed in a joint project involving the following organizations: CPP, the publisher of the whole family of MBTI works; CAPT (Center for Applications of Psychological Type), which holds all of Myers' and McCaulley's original work; and the MBTI Trust, headed by Katharine and Peter Myers.

Step III was advertised as addressing type development and the use of perception and judgment by respondents.


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