ABSTRACT
Data are often available only for recruits, a range-restricted sample. This creates the potential for mistaken inferences and poor decisions. This is because inferences and decisions are about the population, not the sample. Despite these problems, researchers must try to determine statistical values as if the sample was not range-restricted. Although range restriction correction methods have been available for over a century, often they are not applied or are applied incorrectly. Technical psychometric discussions of range restriction have not improved researcher practice. As an alternative, realistic scenarios are presented to illustrate and explain the consequences of (1) failing to correct correlations, (2) using the wrong correction formula, (3) correcting when information about previous selection variables is unavailable, (4) using an inappropriate unrestricted sample, (5) incorrectly computing the confidence interval for corrected correlations, and (6) interpretation of results. Although there are situations under which correction has little effect, correction still provides better estimates of relations among variables. It also improves theoretical understanding and interpretation of real-world results.
ABSTRACT
INTRODUCTION: The assessment of individuals on abilities or other characteristics is based on comparison to a representative sample. General population norms provide an appropriate reference group when the distribution of scores in the sample can be expected to be similar to those for the general population (e.g., comparing high school students at a particular school to national high school norms on a college entrance test). Specialized norms are needed, however, when subsets of the population differ from the population at large. Military pilot trainees represent a special population; they are highly screened on cognitive ability and other characteristics thought to be related to job performance. Other characteristics (e.g., personality) are thought to be "self-selected," resulting in distinctive profiles. Normative tables were developed for U.S. Air Force pilot trainees for two widely used tests, the Multidimensional Aptitude Battery-II (MAB-II) and NEO Personality Inventory-Revised (NEO PI-R). METHODS: The MAB-II and NEO PI-R were administered to large samples of USAF cadets, ROTC students, and officers selected for pilot training. RESULTS: The mean MAB-II full-scale IQ was about 1.5 SD above the adult population norm and was much less variable, supporting the need for specialized norms. Tables showing the percentile equivalents are provided for use by clinicians. DISCUSSION: Use of these tables, in addition to, or in lieu of, commercially published norms, will prove helpful when clinical psychologists perform assessments on pilots; in particular when evaluating them for return-to-duty status following a disqualifying condition that may have affected cognitive functioning or emotional stability. Carretta TR, King RE, Ree MJ, Teachout MS, Barto E. Compilation of cognitive and personality norms for military aviators. Aerosp Med Hum Perform. 2016; 87(9):764-771.
