Ethnic Group Differences in Cognitive Ability Test Scores within a New Zealand Applicant Sample

Article excerpt

Given the widespread use of cognitive ability tests for employment selection in New Zealand, and overseas evidence of substantial ethnic group differences in cognitive ability test scores, a study was conducted to examine the extent to which cognitive test score distributions differ as a function of ethnicity within a New Zealand sample. An examination of 157 Maori and 82 European verbal and numeric ability test scores from within a New Zealand government organisation revealed sizeable and statistically significant mean differences between the two ethnic groups on two of three cognitive tests evaluated. Specifically, Maori scored, on average, 0.55 standard deviations lower than European applicants on a measure of verbal reasoning, and 1.79 standard deviations lower on a measure of numerical business analysis. No mean difference was observed between ethnic groups for a test of general numeric reasoning. In light of these substantial differences on two of the three tests, we discuss strategies that organisations using cognitive tests can employ to minimize adverse impact on Maori applicants, as well as further research that is needed.


Many organisations in New Zealand strive to achieve multiple objectives with their personnel selection procedures, including maximizing both predictive validity and selection utility (i.e., cost effectiveness), as well as achieving and maintaining an ethnically diverse workforce. These goals, however, can conflict, such that selection methods that achieve one goal (e.g., predictive validity) work against another goal (e.g., diversity).

Overseas research suggests that a cognitive ability test is such an example of a selection method that supports one goal at the expense of another (Huffcutt & Roth, 1998; Roth, Bevier, Bobko, Switzer & Tyler, 2001). Cognitive ability tests have been found to be one of the most valid forms of predicting future job performance for a wide range of jobs (Schmidt & Hunter, 1998). For this reason, some authors have suggested that abandoning their use in employment decisions would result in a substantial sacrifice in workforce productivity (Gottfredson, 1994; Hunter & Hunter, 1984). Indeed, Schmidt and Hunter (1998) have argued that, since cognitive ability tests have such high predictive validities, other selection methods should simply be considered as adding incremental validity to the selection decision once the cognitive ability of the candidate has been assessed, implying that cognitive ability testing should be a major component of a thorough selection practice for many jobs. While more recent reviews of the validity of alternative selection methods suggest that, when estimates of range restriction and criterion reliability are standardized across studies, structured employment interviews are at least as valid (Robertson & Smith, 2001), if not slightly more valid (Hermelin & Robertson, 2001) than cognitive ability tests, cognitive ability tests clearly remain one of the more valid predictors of job performance.

Cognitive ability tests play a prominent role in the personnel selection systems of many organisations both overseas and in New Zealand. In a recent survey of selection practices within 100 randomly selected New Zealand organisations and 30 recruitment firms, Taylor, Keelty and McDonnell (2002) found that almost one-half of the organisations sampled use cognitive ability tests for selecting managerial personnel--over twice the proportion used a decade ago (Taylor, Mills & O'Driscoll, 1993)--and that almost two-thirds of recruitment firms use cognitive tests in selection. In fact, the use of cognitive tests in personnel selection is now greater in New Zealand than in many other countries, according to a recent cross-national survey of staff selection practices in 18 countries. This survey found that the prevalence of cognitive ability test use in New Zealand was greater than all but three other countries (Ryan, McFarland, Baron & Page, 1999). …


An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.