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The Construct Validity of the MBTI Instrument in Teams

A comparison with the Belbin Self Perception Inventory

Practitioners and academics use various models to explain people's behaviour in teams. Two of the most widely used are the Belbin team roles, measured by the Self Perception Inventory and psychological type, measured by the Myers-Briggs Type Indicator. As both models are used for team building and development, it is useful to know how they relate to each other. Both suggest that heterogeneous teams which include a range of types will be more effective. There are also clear differences between the models, which may in practice complement each other.

This study was designed to investigate the relationship between the two models. It was intended to provide evidence of the construct validity of both the MBTI instrument and the SPI and to offer insights into how the two models could be used together by practitioners.

• Hypotheses
• Design
• Results
• Conclusions
• References

Hypotheses

The following hypotheses were tested:

• "Plants" would be more likely to be intuitive, and possibly introverted, types, and in particular INTJ and INFJ
  
  
• "Resource investigators" would be more likely to be extraverted, intuitive and perceiving types and in particular ENFP and ENTP
  
  
• "Shapers" would be more likely to be sensing, thinking and possibly perceiving types, and in particular ESTP and ESFP
  
  
• "Completer-finisher" would be more likely to be sensing and judging types and in particular ISTJ and ISFJ
  
  
• "Monitor-evaluators" would be more likely to be introverted, thinking and possibly intuitive types and in particular INTP and ISTP
  
  
• "Implementers" would be more likely to be sensing and judging types and in particular ESTJ and ENTJ
  
  
• "Co-ordinators" would be more likely to be feeling and judging types and in particular ENFJ and ESFJ
  
  
• “Team workers” would be more likely to be feeling types and in particular ISFP and INFP.

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Design

The study made use of a set of opportunistic samples so complex experimental design was not possible. Participants completed both the SPI and the MBTI instruments. No feedback was given until both questionnaires had been completed. Before any data analysis was carried out, expert MBTI users were given full descriptions of the Belbin team roles and asked to develop hypotheses as to the relationships between the two instruments. They were encouraged to look at type dynamics and whole type as well as single type dichotomies. Appropriate statistical techniques were used to establish whether these hypotheses were supported.

The sample consisted of 106 individuals from six different organisations who had completed both the SPI and the MBTI questionnaires as part of a separate project. Consultancy, retail, advertising, sales and marketing sectors were represented. The mean age was 32 years. 39% of the group were managers, 61% were male, and 89% were from the majority ethnic group.

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Results

Independent-samples T-tests were carried out to establish, for each type dichotomy, whether there was a significant difference in Belbin scores between the two types. Five of the ten firm hypotheses on single type were supported.

Results of T-test on Single Type

Only two of the eleven more speculative hypotheses on single type were supported.

MBTI continuous scores were available for a subset of the sample (n=41). These scores were correlated with scores on the Belbin questionnaire. The results broadly supported the hypotheses, with for example a strong correlation between scores on Plant and Sensing-Intuition (S-N). Plants tended to be more intuitive.

A one-way analysis of variance was used to investigate differences in Belbin scores between the 16 different MBTI types. A significant trend was demonstrated for Shaper, Implementer and Team Worker, but not for Plant, Resource Investigator, Completer, Monitor-Evaluator and Co-ordinator. Where a significant trend was revealed, however, post-hoc tests showed that the differences between MBTI types were as predicted.

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Conclusions

The results of this study should be treated with caution for a number of reasons. The sample size meant that the representation of some MBTI types was very small. Also, the SPI does not claim to have robust psychometric properties. Nevertheless, some useful conclusions can be drawn.

The trends in the data do in general terms support the hypotheses and provide some construct validity for the Belbin questionnaire and for the use of the MBTI instrument in teams.

Both instruments suggest that diversity is essential for the health of the team and that learning about roles and personality is crucial.

The results suggest that the two questionnaires, and therefore the models from which they are drawn, are not antagonistic to each other. The two could be used together by practitioners in order to gain a fuller understanding of how individuals function in teams. The SPI takes a face valid approach, while the MBTI arguably looks at deeper and more enduring aspects of personality. Apparent “mismatches” between the two instruments can give insights into team and individual issues. Is an individual's team role the most comfortable or preferred one for them (as measured by the MBTI), and what effect does this have on the individual or the team?

The results also suggest that there may be some value in linking team roles with the 8 dominant functions, and that therefore there could be some merit in using type dynamics more overtly in teams. This area is sometimes neglected by MBTI practitioners, because of time and other pragmatic considerations.

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References

Belbin, R M (1981). Management Teams. Oxford: Heinemann

Hammer, A L, and Huszczo, G E (1996). Teams. In A L Hammer (Ed.), MBTI applications; a decade of research on the Myers-Briggs Type Indicator (pp. 81-104). Palo Alto: Consulting Psychologists Press.

Hirsh, S K (2000). Introduction to Type and Teams (European English Edition). Oxford: Oxford Psychologists Press.

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