Optimal combination of personality and intelligence

Personality and intelligence are both related to job performance, but how should they be weighted for optimal results? The most straightforward approach is a linear combination, and indeed there is little evidence for other types of models. Once this is decided the final question is what weights should be given to the two types of information, in order to maximize predictive efficiency. It is well-known that they tend to be uncorrelated, hence the crucial question is how valid they are in relation to job performance criteria. Intelligence, or GMA (the g factor) correlates around 0.6 with job performance (Schmidt & Hunter, 1998). "Personality" is a less stringent term, and could mean many things. However, I shall take personality as referring to an optimal index of subscales, and such indices have been found to correlate around 0.55 with job performance (de Colli, 2011; Sjöberg, 2010; Sjöberg, Bergman, Lornudd, & Sandahl, 2011), after correction for measurement errors in criteria and range restriction in the independent variable (Schmidt, Shaffer, & Oh, 2008). Hence, intelligence and personality, in this sense, are equally efficient as predictors and an evidence-based strategy is to treat them that way, with equal weights.

It should be noted that the usual Big Five dimensions are much weaker predictors of job performance, as shown in a number of meta-analyses (Barrick, Mount, & Judge, 2001). To get an efficient personality predictor it is necessary to form an index based on focused and narrow scales (Bergner, Neubauer, & Kreuzthaler, 2010; Christiansen & Robie, 2011; Sjöberg, 2010/2012). Big Five personality tests are not sufficient for optimal prediction of job performance.

References

Barrick, M. R., Mount, M. K., & Judge, T. A. (2001). Personality and performance at the beginning of the new millennium: What do we know and where do we go next? International Journal of Selection and Assessment, 9, 9-30.

Bergner, S., Neubauer, A. C., & Kreuzthaler, A. (2010). Broad and narrow personality traits for predicting managerial success. [doi:10.1080/13594320902819728]. European Journal of Work and Organizational Psychology, 19, 177-199.

Christiansen, N. D., & Robie, C. (2011). Further consideration of the use of narrow trait scales. [doi:10.1037/a0023069]. Canadian Journal of Behavioural Science/Revue canadienne des sciences du comportement, 43, 183-194.

de Colli, D. (2011). Ett nytt svenskt arbetspsykologiskt test och arbetsprestation inom polisen – samtidig validitet: Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.

Schmidt, F. L., & Hunter, J. E. (1998). The validity and utility of selection methods in personnel psychology: Practical and theoretical implications of 85 years of research findings. Psychological Bulletin, 124, 262-274.

Schmidt, F. L., Shaffer, J. A., & Oh, I.-S. (2008). Increased accuracy for range restriction corrections: Implications for the role of personality and general mental ability in job and training performance. Personnel Psychology, 61, 827-868.

Sjöberg, L. (2010). Upp-testet och kundservice: Kriteriestudie. Forskningsrapport 2010:6. Stockholm: Psykologisk Metod AB.

Sjöberg, L. (2010/2012). A third generation personality test (SSE/EFI Working Paper Series in Business Administration No. 2010:3). Stockholm: Stockholm School of Economics.

Sjöberg, L., Bergman, D., Lornudd, C., & Sandahl, C. (2011). Sambandet mellan ett personlighetstest och 360-graders bedömningar av chefer i hälso- och sjukvården. Stockholm: Karolinska Institutet, Institutionen för lärande, informatik, management och etik (LIME).

Job interest and performance: a revised view

Is job interest of any importance to job performance? It seems very likely that it should be, but as pointed out by Nye et al. (Nye, Su, Rounds, & Drasgow, 2012), "interest measures are generally ignored in the employee selection literature" (p. 384). Part of the reason seems to be that previous meta-analytic work reported a very low correlation between interest and performance, only about 0.1 (Hunter & Hunter, 1984). However, Nye at al. criticized the often cited meta-analysis published by Hunter and Hunter and conducted a very extensive new analysis of the relation between interest and performance. They came up with a different conclusion: for studies where the interest scales matched the character of the jobs, the estimated correlation was 0.36, after correction for measurement errors and indirect range restriction. They concluded that interest should be considered in selection contexts. 

This is not the only example showing that earlier meta analyses of the effectiveness of predictors of job performance may be quite misleading. A recent publication on integrity tests by van Iddekinge et al. (2012) showed that earlier meta analytic work (Ones et al., 1993), cited by Hunter and Hunter, grossly over-estimated the validity of integrity tests.

The recent Nye at al. work  is undoubtedly very important. However, even stronger results can probably be obtained with specific interest measures. Vocational interest does not measure interest in a specific job, but in a class of jobs. In the UPP test, we measure routinely interest in the specific job under consideration, either in selection or in various types of follow-up. As an example, data from a study of employees in customer service in a finance company (Sjöberg, 2010) was re-analyzed. The correlation between job (not vocational) interest and supervisor rated performance on core job tasks was 0.55, after correction for measurement error and indirect range restriction. The specific interest measure is proximal to job performance, while vocational interest is distal, hence it should be expected to have a lower correlation.

What creates interest (Sjöberg, 2006)? For a given task content, optimal challenge may be the answer to the question. Interests are also probably somewhat elastic, i.e. you may develop a new interest under favorable circumstances (support, optimal challenge). Maybe one should try measure not only interest but also potential for developing interest. In a selection situation, it must be expected that interest scores are contaminated with impression management, and there is a need to correct for that factor. Alternatively, indirect measurement can be attempted, such as knowledge of facts. People who are strongly interested inform themselves about a job or area of study, hence know more. I tried this idea in the selection of applicants to the Stockholm School of Economics, with some success.

References

Hunter, J. E., & Hunter, R. F. (1984). Validity and utility of alternative predictors of job performance. Psychological Bulletin, 96, 72-98.

Nye, C. D., Su, R., Rounds, J., & Drasgow, F. (2012). Vocational interests and performance: A quantitative summary of over 60 years of research. Perspectives on Psychological Science, 7(4), 384-403.
Ones, D. S., Viswesvaran, C., & Schmidt, F. L. (1993). Comprehensive meta-analysis of integrity test validities: findings and implications for personnel selection and theories of job performance. Journal of Applied Psychology Monograph, 78, 679-703.
Van Iddekinge, C. H., Roth, P. L., Raymark, P. H., & Odle-Dusseau, H. N. (2012). The criterion-related validity of integrity tests: An updated meta-analysis. [doi:10.1037/a0021196]. Journal of Applied Psychology, 97(3), 499-530.

Sjöberg, L. (2006). What makes something interesting? (Review of the book, Exploring the psychology of interest by Paul J. Silvia). PsycCRITIQUES, 51 (46, Article 4), No Pagination Specified.

Sjöberg, L. (2010). UPP-testet och kundservice: Kriteriestudie. (The UPP test and customer service: A criterion study). Forskningsrapport 2010:6. Stockholm: Psykologisk Metod AB.
Sjöberg, L. (2010/2012). A third generation personality test (SSE/EFI Working Paper Series in Business Administration No. 2010:3). Stockholm: Stockholm School of Economics.
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