What are interest inventories?

Introduction

Since the inception of the interest inventory in the late 1920s, its development in the context of educational and vocational counseling has expanded considerably. The interest inventory is a questionnaire-type device designed to measure the intensity and breadth of an individual’s interests. Most often, the specific interests measured by an inventory relate to a variety of vocational and avocational activities. The term “interest” refers to a very specific aspect of human behavior. An interest is an enduring trait, a predilection for a particular activity, avocation, or object. It is a special attitude that engages the individual and motivates him or her to move toward the object of interest.

An interest inventory is distinct from both an achievement test
and an aptitude test. An achievement test measures an individual’s current ability to perform a particular task. An aptitude test measures potential or capacity for performing that task in the future. An interest inventory, on the other hand, measures a person’s liking for a particular task without reference to the individual’s actual ability to perform the task or potential for doing so in the future. For example, a high school student may show a high interest in the field of nursing. This interest alone, however, does not mean that he or she has any current nursing skills, nor does it indicate that the student has the mental ability, physical stamina, or emotional makeup for success in the nursing field.

What then is the rationale for examining patterns of interest? First, interest in a particular activity provides some motivation for engaging in that activity. Therefore, when one identifies areas of interest, one is also identifying areas in which a person might have the degree of motivation necessary for following through on that activity. Second, the scores obtained from an interest inventory are helpful in pointing out which groups of persons an individual most resembles. Finally, it has been shown that there is some relationship between a person’s domain of interest and the occupational field that that person may eventually choose.

The construction of an interest inventory may be empirically based (that is, based on observation of factual information) or theory-based (based on systematic principles concerning occupational categories). Some inventories have utilized a combination of these approaches. In its development, the empirically based inventory would be administered to various criterion groups of successful persons representing particular occupations. The inventory would also be given to a reference group, a large group representing people in general. The items on the inventory that set apart a particular criterion group from the larger reference group would then become part of the scale for that occupation. A person would be considered to have a high score on a particular occupational scale if he or she has interests that closely match the criterion group’s interests.

Other inventories are simply based on occupational theory. One well-known theory that has been utilized in the construction of interest surveys was first set forth in John L. Holland’s 1992 publication Making Vocational Choices: A Theory of Careers. The theory involved the categorization of occupations into the following six types: realistic, investigative, artistic, social, enterprising, and conventional. Other occupational categories have also been devised and used as the bases for interest inventory construction and scoring. Interest inventories also differ on the basis of the format used in the construction of the items. Some inventories ask the individual to indicate the degree of interest he or she has in a particular activity, whereas others use a forced-choice format, asking the testee to make an either/or choice between two activities.

Popular Inventories

In their book Career Guidance and Counseling Through the Life Span (1996), Edwin L. Herr and Stanley H. Cramer reviewed some commonly used interest inventories. Some of the inventories, such as the well-known Strong Interest Inventory (SII), the Career Assessment Inventory (CAI), and the Vocational Preference Inventory (VPI), yield results based on Holland’s six general occupational themes. Others, such as the Career Occupational Preference System (COPS) and the Vocational Interest Inventory (VII), are constructed around Anne Roe’s eight occupational groups.

Interest inventories also differ in terms of their intended use. The Interest Determination, Exploration, and Assessment System (IDEAS) was developed for grades six through twelve; the Geist Picture Interest Inventory (GPII) is intended for culture-limited and educationally deprived populations; and the Kuder Occupational Interest Survey (KOIS) is designed for high school students and adults. The scope of occupations explored is another variable. The Minnesota Vocational Interests Inventory (MVII) deals with skilled occupations, while the COPS, Form P, deals with professional occupations. Some inventories are hand scored, while others are scored by computer. Tests such as the SII can be computer administered as well. Some of the inventories are designed to be used in conjunction with the Dictionary of Occupational Titles, published by the US Employment Service, or the
Occupational Outlook Handbook, published by the U.S. Department of Labor, Bureau of Labor Statistics, and available online. The KOIS and the Ohio Vocational Interest Inventory (OVII) are two such examples.

There are various ways to judge the relative value or dependability of these measurement devices. First of all, one must consider the reliability of the inventory. Interests are human traits with a somewhat enduring quality. They are not expected to change radically over a short period of time. The reliability of the inventory is a measurement of how stable scores on the inventory would be if the inventory were administered to the same person over a period of time.

A second consideration in determining the value of an inventory is its validity. Though there are many ways to approach test validity, the aim is to determine if the inventory is really measuring interests as opposed to some other trait. Studies are often undertaken to see if scores on one interest inventory are consistent with scores on another interest inventory that is considered to be a valid measure. Another test of validity involves giving the interest inventory to persons in that occupation to see if their interest scores emerge in the direction expected. Information about the specific reliability and validity of a particular interest inventory is reported in the manual developed for its use.

Of particular concern in evaluating an interest inventory is the possibility of sex-role bias. The extent to which an interest inventory is constructed to perpetuate stereotypical male and female roles is a major issue. The SII, for example, attempted to use both male and female criterion groups for each occupation on the inventory. This posed some problems, such as finding sufficient numbers of males or females in certain occupations. Care was also taken in revisions to eliminate inappropriate references to gender; for example, “policeman” was changed to “police officer.”

Inventory Uses

Interest inventories are typically used in educational and vocational counseling. Most interest inventories are devised to assist a person in pinpointing possible career options. This entails assessing not only his or her interests in terms of particular careers but also interests related to college majors. Often an interest inventory will be helpful in determining where an individual’s interests lie in relation to larger clusters of occupational groupings. Interest inventories are also used by researchers in obtaining information about the vocational interests of specific groups for the purpose of planning and implementing career training programs and noting overall occupational trends.

The following case study serves as an illustration of the practical use and interpretation of the interest inventory. It includes a student profile based on the KOIS and the recommendations that a counselor might make to this student in the light of the results obtained.

“John” is a seventeen-year-old adolescent in his junior year of high school. He is enrolled in a college preparatory program and has often verbalized at least a tentative interest in following in the footsteps of his father, who works in commercial real estate appraisal. His grades in art and drafting classes indicate that he has a propensity for visual thinking and illustration. John would be the first to admit, however, that his interests are very practical in nature, and he is not drawn toward philosophical debates. John’s entire class was administered the KOIS through the counseling and guidance department of his school. The tests are computer-scored, and results are distributed to the students during individual appointments with the school counselor.

John’s KOIS report form indicates that his results appear to be dependable. His interests in ten vocational activities are ranked in order of his preference for each. As compared with other males, his top interests, which are literary, persuasive, artistic, and mechanical, are average in intensity. The two areas ranked least interesting to John are social service and musical. John’s patterns of interest as compared with men in many different occupations are most consistent with auto salesperson, photographer, travel agent, buyer, retail clothier, radio station manager, and real estate agent. Furthermore, John shows an interest pattern most similar to men in the following college majors: business administration, physical education, economics, and engineering.

John’s counselor reminds John that the KOIS measures interests, not aptitudes or other personal variables that are part of a successful career match. The counselor observes that John’s KOIS profile does accentuate some of the areas of interest to which John has alluded during his high school years. She notes that on the KOIS there were several indications that John might like an occupation related to business and sales.

As a follow-up to the KOIS, the counselor points out that John could benefit from exploring various school programs that offer the college majors that surfaced on his report form. She encourages John to talk to college representatives about his particular interests. She suggests that John look into some of the occupations that appeared on his KOIS report and possibly utilize such resources as the US Department of Labor’s Guide for Occupational Exploration in learning about working conditions, employment prospects, promotion opportunities, and related occupational opportunities. The counselor also encourages John to talk with persons working in those general areas of employment that appeared on his KOIS. Exploration of other careers in the same job families as those which appeared on his report form might also prove beneficial. For John, the KOIS is probably the most beneficial in providing him with the impetus for continued career exploration.

The counselor, in perusing all the scores of the junior class members with whom she is working, may note overall patterns of interest appearing in the KOIS report forms. This information may lead her to make certain provisions for those interests in the school’s career awareness program, in the type of invited speakers, and in the kinds of college and training program representatives invited to make presentations at the school.

While John was given the opportunity to take an interest inventory in high school, there are other situations in which a person may do so. Professional career counselors offer such opportunities to interested parties through college and university career centers and vocational rehabilitation services, in workshops for those planning second careers, and in private practice settings.

Vocational Counseling

Interest inventories can be situated in the overall context of vocational counseling, a field whose origins stemmed from the focus on job productivity and efficiency that arose during the Industrial Revolution. Frank Parsons is credited with laying the foundation for the field of career development. In his book Choosing a Vocation (1909), Parsons articulated a conceptual framework for career decision making. He emphasized that career decision making must be based on a clear understanding of one’s personal attributes (such as aptitudes, interests, and resources) as related to the requirements of the job field. Parsons’s theory provided the theoretical backdrop for the more scientifically oriented trait-factor approach to vocational counseling that would soon follow.

Getting displaced American workers back on the job was a major impetus in vocational counseling after the Great Depression of the 1930s. During that era, the University of Minnesota became a center for the development of new assessment devices to measure individual differences, and researchers there designed instruments that became part of test batteries used in counseling centers around the country. E. G. Williamson’s work in career counseling research led to the publication of the Dictionary of Occupational Titles by the U.S. Employment Service in 1939. D. G. Paterson and J. G. Darley were also prominent among those psychologists who developed what is referred to as the “Minnesota point of view,” or trait-factor theory.

Trait Factor Theory

This trait factor approach has been the basis for many of the interest inventories that have been devised. Attempts were made to match the personal traits (in this case, interests) of the individual with the requirements of particular careers and job environments. The interest inventories have been the most widely used.

The most popular interest inventory is the Strong Interest Inventory. The first version of the SII was published in 1927 by Edward K. Strong, Jr., from Stanford University; this inventory has been in use ever since. At that time it was known as the Strong Vocational Interest Blank, a project on which Strong worked tirelessly, revising and improving it until his death in 1963. In that same year, David P. Campbell at the University of Minnesota Center for Interest Measurement Research assumed the task of continuing to update Strong’s work. Along with Jo-Ida Hansen, Campbell produced the interest inventory that was redesignated the Strong-Campbell Interest Inventory in its fourth (1985) edition. The 1997 edition, however, was published under the name of the Strong Interest Inventory, and subsequent versions of the inventory have retained that name.

Probably the most common alternative to the SII is the Kuder Occupational Interest Survey, which was first published by G. Frederic Kuder as the Kuder Preference Record. Differences can be noted between the KOIS and the SII in terms of their technical construction and scales.

Although many interest inventories have been devised since the idea was first conceived, most of these inventories have focused on interests in career activities and related college majors. The 1970’s, however, brought about the notion of inventories designed to measure leisure interests. Richard N. Bolles, in his book The Three Boxes of Life (1981), indicated that, in addition to meaningful work, people need to engage in the pursuit of two other “boxes,” that of learning/education and that of leisure/playing. This more holistic approach may be more evident in the interest inventories yet to be developed.

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