Other Classification Systems
More extensive discussion of classification systems can be found elsewhere (see Herr and Cramer  or Isaacson ). We will consider briefly a sample of widely used groupings.
Roe (1956) prepared a two-dimensional system that combines a horizontal grouping according to primary focus of activity and a vertical grouping based on level of function. The primary focus used for the horizontal axis includes eight groups clustered according to kinds of activities. These categories are largely based on earlier interest measurement research. The reader will readily note aspects of the antecedents of both the Strong-Campbell Interest Inventory and the Kuder General Interest Survey. The eight groups make up the outer circle in the series of concentric circles. The eight areas comprising the horizontal axis are:
VII. General culture
VIII. Arts and entertainment
The vertical axis is labeled "level of function," which includes the degree of responsibility, capacity, and skill. When these three components do not correlate closely, the first (degree of responsibility) is given basic emphasis. The six levels of function include the following:
1. Professional and managerial-independent responsibility.
2. Professional and managerial-other.
3. Semiprofessional and small business.
Roe has categorized typical occupations using these two dimensions.
Holland's (1973) theory of vocational choice: One will recall that he postulated that there are six working environments, each of which attracts like-minded individuals. Further, since not all work settings are purely one type or another, various combinations of these six can be made with any one category considered primary and different types having secondary and tertiary impact. Holland thus suggests that the various occupations can then be represented by three-letter codes arranged in the order of influence exerted by the six environmental types. The Self-Directed Search demonstrates a relationship between an interest-type measurement instrument and an occupational classification system. The Occupations Finder, used in conjunction with the Self-Directed Search, lists the three-letter codes assigned by Holland to an array of occupations. The six types include Realistic, Investigative, Artistic, Social, Enterprising, and Conventional, arranged clockwise in that sequence around a hexagon. The Holland code for counselor, for example, is SEA. This would be translated to mean that the typical counselor's work is most similar to social occupations, with a secondary component involving enterprising aspects, and a lesser, third component of artistic characteristics.
The World of Work Map for job Families (Hanson, 1974) presents another two-dimensional approach to classifying occupations, based on research completed by the staff at American College Testing Program. This research suggests that most occupations relate to two fairly independent bipolar dimensions. One of these, the horizontal continuum, is a people-things relationship and the other, the vertical continuum, is a data-ideas dimension. Further, ACT research postulates that as an occupation's involvement with one of these factors places it nearer one extreme of these two continua, its relationship to the other extreme diminishes. Expressed in another way, one might suggest that New York and San Francisco represent the two ends of a similar continuum, so the nearer one is to New York, the farther one is from San Francisco. Similarly, we might picture another continuum running from Winnipeg to Monterey, intersecting the first at approximately Omaha. The four quadrants thus produced show relationships between the extremes of each continuum. Each quadrant can then be divided into three regions to represent the two areas where one or the other relevant extreme is the more influential and the middle region reflects equal influence. Similarly, an area surrounding the intersection of the two continua can represent a region where the four extreme factors are relatively balanced.
Various job families, or clusters, can then be assigned to appropriate regions according to the relative weights of the pertinent extremes. For example, Education and Social Services is heavily people-oriented and slightly idea-oriented; consequently, it is plotted well to the left on the people-things continuum and slightly below the midpoint on data-ideas (approximately at Las Vegas on our geographic illustration). On the other hand, Natural Sciences and Mathematics is considered to be fairly heavily loaded with ideas and things, so it falls in the mid-area of the lower right quadrant, geographically near Atlanta.
These thirteen areas (twelve sectors and one middle area) accommodate twenty-three different occupational groups called job families. The system includes two other families not presently plotted on the map because of the incohesive nature of these two groups.
D'Costa and Winefordner (1969) developed a three-dimensional occupational classification system using the data-people-things concept. Visualizing the world of work as a cube, one can use one factor for each dimension of the cube. If one uses the front left lower corner of the total cube as the starting point, the data continuum can be viewed running from front to back, the people continuum from left to right, and the data continuum from bottom to top.
Because the gradations in each of the three hierarchies are not discrete and precise, they used a three-step division for each-low, average, and high. For convenience, numbers were assigned to each of the three segments, 0 for low, 1 for average, and 2 for high. Further, with each continuum divided into three segments, one now has a three-by-three-by-three matrix of twenty-seven smaller cubes within the total figure, with each smaller cell representing a relationship to data, people, and things. Thus the front left lower cell represents low relationship to all three and can be numerically represented by 0, 0, and 0. Similarly, the rear right upper cell reflects high relationship to all three and would be numbered 2, 2, and 2. The middle cell, halfway back, halfway right, and halfway up would be average in all relationships, or 1, 1, 1. The rear right lower cell shows high relationship to data and people, but low relationship to things, and is identified as 2, 2, and 0. This cell would include the previously mentioned occupations of psychiatrist, counselor, lawyer, and speech pathologist, all of which carry a DOT worker function code of .107 (high on data and people, low on things). Similarly, occupations that involve the various combinations of data-people-things relationship can be assigned to the appropriate cell with all other occupations requiring that mix. Only a few occupations require very little or very high involvement with all three; thus 0, 0, 0 and 2, 2, 2 would not be used frequently.
D'Costa et al. (1970) used the Cubistic classification system as a theoretical basis for the Ohio Vocational Interest Survey and OVIS II. The scores obtained on the OVIS are related to occupational clusters located in the various cells.
The General Aptitude Test Battery provides a different basis for classifying occupations. Research with the GATB has been continuous since the original publication of the test in 1947. Testing large groups of workers in various occupations has identified those aptitudes that are critical for successful performance of that occupation. This has led to the preparation of Occupational Aptitude Patterns (OAP) and Specific Aptitude Test Batteries (SATB) consisting of those aptitudes that are significantly related to successful performance in a specific occupation, and those portions of the GATB that produce scores for those aptitudes.
The Occupational Aptitude Patterns identify those occupations that require the same array of skills, even though the occupations may be in very different occupational designation families, or industrial sectors, or involve different interest factors. Research has established the links between the OAP's and worker functions, and between OAP's and the work groups used in the Guide for Occupational Exploration. Appendix B in the Guide lists the occupations by GOE work group and subgroup for which Specific Aptitude Test Batteries have been determined. There are now approximately 450 SATB's consisting of combinations of two, three, or four aptitudes with established cutting scores on the appropriate GATB parts for specific occupations. The specific SATB information is provided in the Manual for the GATB.