Strong Interest Inventory

The Strong Interest Inventory (SII; publisher: Consulting Psychologists Press, www.cpp.com) first was published by Edward K. Strong, Jr., in 1927. Over the decades, this measure of vocational interests has been updated and expanded appreciably. By virtue of its long history, the SII is one of the most well-documented instruments available for use by assessment experts. Clients find SII scores useful for making vocational and educational decisions, confirming occupational choices, suggesting new directions within a career, understanding job dissatisfaction, and developing plans for retirement. The questionnaire, which takes about 30 minutes to complete, includes 291 items. The profile reports five types of scales—General Occupational Themes, Basic Interest Scales, Occupational Scales, Personal Style Scales, and Administrative Indexes.

The General Occupational Themes are designed to measure John Holland's vocational types—Realistic (building, working with machines), Investigative (researching, analyzing data), Artistic (creating, writing, performing), Social (helping others, teaching), Enterprising (selling, leading), and Conventional (paying attention to detail, organizing). The Basic Interest Scales (BIS) cover 30 content areas, each of which is clustered according to its strongest relation with Holland's vocational types. For example, Realistic BIS includes mechanics and construction, Investigative BIS includes medical science, Artistic BIS includes visual arts and design, Social BIS includes counseling and helping, Enterprising BIS includes entrepreneurship, and Conventional BIS includes office management. The General Occupational Themes and the BIS are normed on a large sample of employed women and men.

The Occupational Scales measure the interests of 122 occupations, drawn from a wide array of professional, technical, and nonprofessional jobs, with separate sex-normed scales reported for each occupation (i.e., a total of 244 Occupational Scales). The scores for these scales reflect the similarity of a client's interests to those of people in the occupation.

The Personal Style Scales measure an individual's work and learning style. Work Style is designed to distinguish between people who like working with others (e.g., school counselors) and those who prefer working with data, things, and ideas (e.g., mathematicians). Learning Environment identifies people who prefer academic environments (e.g., sociologists) versus those who prefer hands-on environments (e.g., auto mechanics). Leadership Style differentiates people who like to take charge (e.g., school administrators) and those who prefer to follow (e.g., production workers). Risk Taking identifies people who like risky activities (e.g., firefighters) and those who are cautious (e.g., librarians). Team Orientation contrasts [Page 972]those who prefer team-based activities (e.g., nursing home administrators) and those who prefer working alone (e.g., medical illustrators).

Studies have demonstrated the reliability of SII scale scores over short and relatively long periods of time. An extensive body of literature also reports evidence of validity for SII scores for use with clients who vary in age, ability, ethnicity, and interest orientation.