review of the psychometrics and uses of the VI are contained in Hol-
land, Johnston, & Asama (1993).
The relationships among these four diagnostic-theoretical indi-
cators (congruence, consistency, differentiation, identity) and their
use as interpretive ideas, as well as organizing or theoretical con-
structs, is described in detail in Table 9.2. Here again, we are just
beginning to understand how and why some individuals develop a
sharp spike in one type, whereas others develop strong interests in
three or four types. All things being equal, however, an individual
with high identity who is congruent, consistent, and differentiated
should be more predictable and better adjusted than one who is
incongruent, inconsistent, and undifferentiated. “For example, a con-
ventional-enterprising person whose personality pattern is consistent
and differentiated and who enters a conventional-enterprising envi-
ronment with a high degree of differentiation will probably do com-
petent work, be satisfied and personally effective, and engage in
appropriate social and educational behavior” (Holland, 1997, p. 40).
Application of the Holland Organizing Schema to Occupational
Environments. Occupational environments are classified in a man-
ner similar to the classification of personality types. A census can be
conducted of the percentage of employees of a given type in an or-
ganization (Holland, 1997), thus characterizing its “personality
pattern.” Consistency and differentiation can be calculated by
examining the three-letter code that results from the census. Iden-
tity of a work setting is calculated by estimating the number of dif-
ferent occupations present. A large number of different occupations
would result in a diffuse identity, whereas a small number of occu-
pations would result in a focused identity (Holland, 1997). For
example, a small or medium-sized accounting firm might consist of
eight to ten accountants whose codes would cluster around C (CIS,
CES, and so on), and five or six accounting clerks whose codes
would also cluster around C (CIS, CIE, and so on), and perhaps
several secretaries whose codes would also cluster around C (CSA).
HOLLAND’S THEORY 385