Age differences in personality traits from 10 to 65: Big Five domains and facets in a large cross-sectional sample.

TL;DR: The use of rigorous qualitative research methods can enhance the development of quality measures, the development and dissemination of comparative quality reports, as well as quality improvement efforts, and is described.

Abstract: Since the first version of this chapter (John, 1990) was completed in the late 1980s, the field of personality trait research has changed dramatically. At that time, the Big Five personality dimensions, now seemingly ubiquitous, were hardly known. Researchers, as well as practitioners in the field of personality assessment, were faced with a bewildering array of personality scales from which to choose, with little guidance and no organizing theory or framework at hand. What made matters worse was that scales with the same name might measure concepts that were quite different, and scales with different names might measure concepts that were quite similar. Although diversity and scientific pluralism can be useful, systematic accumulation of findings and communication among researchers had become almost impossible amidst the cacophony of competing concepts and scales. At the University of California, Berkeley, for example, researchers studied personality with as few as two, and as many as 20 concepts, including the two dimensions of egoresilience and egocontrol that Block and Block (1980) measured with their California Q-sort; the four scales on the Myers– Briggs Type Indicator (MBTI; Myers & McCaulley, 1985) that measure extraversion, feeling, judging, and intuition; and the 20 scales on the California Psychological Inventory (CPI; Gough, 1987) measuring folk concepts such as capacity for status, selfcontrol, wellbeing, tolerance, and achievement via independence (see Table 4.1). At the time, many personality researchers were hoping to be the one who would discover the right structure that all others would then adopt, thus transforming the fragmented field into a community speaking a common language. However, we now know that such an integration was not to be achieved by any one researcher or by any one theoretical perspective. As Allport once put it, “each assessor has his own pet units and uses a pet battery of diagnostic devices” (1958, p. 258). What personality psychology lacked was a descriptive model, or taxonomy, of its subject matter. One of the central goals of scientific taxonomies is the definition of overarching domains within which large numbers of specific instances can be understood in a simplified way. Thus, in personchAPTeR 4