Basic Interest Scales
The basic interest scales were designed to provide specific information about the likes and dislikes of the respondent. The 25 basic interest scales of the Strong Interest Inventory measure more specifically the homogenous interest areas measured by the General Occupational Themes. Each scale focuses on a narrow, concentrated interest area. Scores on these 25 scales represent individuals’ vocational and life-style interests but with greater specificity. It provides greater specificity of interests than do the general occupational themes and are, therefore, typically more predictive of occupation. The 25 scales are agriculture, nature, military activities, athletics, mechanical activities, science, mathematics, medical science, music/dramatics, art, applied arts, writing, culinary arts, teaching, social service, religious activities, public speaking, law/politics, merchandising, sales, organizational management, data management, computer activities and office services.
Occupational Scales
Occupational scales were designed to provide information about the degree of similarity between the examinee’s interests and those of selected occupational criterion groups. Each occupational scale was empirically derived by comparing the responses given by a sample of workers in an occupation with those given by a general, nonspecific sample of people and selecting only those items that significantly differentiated the two groups. They were designed to discriminate between Men in General/Women in General and people in specific occupation. The results of the scale are allowed to compare the interest of the participant to those of men who are satisfactorily employed in 104 occupations. Unlike the General Occupational Theme and the Basic Interest Scales, on which the “likes” are compared to a general group of people, the Occupational Scales compare both likes and dislikes to those of people who are satisfied working in that occupation.
Scores are T scores, normed against those in particular occupation. The results of the Occupational Scales can indicate specific occupations that the participant may find interesting and the related occupations that he/she may find interesting. They can also identify the kinds of people he/she might enjoy working with, and help him/her consider occupational possibilities that he/she may never has thought of before.
Personal Style Scales
The four Personal Style Scales provide additional insight into how comfortable the test taker is in activities and situations in which he/she finds him/herself, at work, home, and leisure. The results on the Personal Style Scales can suggest how he/she might like to go about doing a job or task. Box-and-whisker is used to present the result of this scale. The box shows the middle 50% (mean score), while the whiskers show the middle 80% of scores for each gender. All four scales are designed so that the mean score (average) is 50. People who score 45 or lower tend towards the left end of the scale, while those who score 55 or and above tend to identify with the right pole. People who score between 46 and 54 often have no predominant preference for one style or another; they frequently have a mix of preferences. For those who score at the extremes (below 40 or above 60), the preference clarity is greater.
These scales are bipolar and thus the score only shows the direction, not good or bad. A low score is fine and it doesn't mean something is wrong with that person. Likewise, a high score does not mean better. It merely shows which pole, or direction, the person feels most comfortable with and both poles are equally good.
Work Style Scale
The Work Style scale indicates whether the test taker prefers to work with other people or whether he/she prefer to work alone with ideas, data or things. Those who score high on the Work Style scale prefer to work with people and endorse a number of items that represent occupations and activities that are people oriented. There are 51 items scored on the scale. Six of the items ask the respondent to indicate preferences for working with people or for working with ideas, data, and things. In addition to the 6 dichotomous items in the Preferences in the World of Work section of the answer sheet, 45 items throughout the Strong are scored on this scale.
Learning Environment Scale
The Learning Environment Scale indicates the setting in which one feel most comfortable learning. It suggests whether he/she is more interested in learning abstract, theoretical concepts through reading, lectures, and discussion or interested in learning practical skills and how to solve applied problems through hands-on experience. This scale does not measure academic ability. A high score on this scale reflects interests in cultural, verbal, and research activities, as well as teaching, rather than interests in clerical, technical, and physical activities. Individuals with higher scores report interests in activities and occupations that require extensive academic study and professional training. Scores for this scale are obtained from the 49 items throughout the Strong that best differentiate a liking for formal academic settings and a liking for more applied settings.
Leadership Style Scale
The Leadership Style Scale measures your interest in either assuming a leadership style that is directive and outspoken, or leading by example. This scale does not measure your interest in being a leader, nor does it indicate one’s probability of success as a leader. A high score on this scale reflects an interest in interpersonal and organizational activities and occupations. The Leadership Style scale is made up with 23 homogenous items.
Risk Taking/Adventure Scale
The Risk Taking/Adventure Scale indicates how comfortable the test taker is taking risks. A high score on the scale indicates a willingness to act spontaneously and sometimes recklessly. Low scores reflect a preference for taking precautions. Women tend to score lower on this scale than do men. Scores also tend to decrease with age and thus, the scale is said to be more predictive of current than future behavior
Practical Evaluation
The SII yields three kinds of interest scores. The first scores reflecting the extent to which the respondent is interested in various types of people, data, and activities. The second scores reflect the extent to which the respondent's people, data, and activity interests are consistent those of workers in the six major occupational types (realistic, artistic, investigative, social, enterprising, conventional). The final ones reflect the extent to which the respondent's interests are consistent with those expressed by representative samples of workers in more than 100 specific occupations.
Based on the pattern of scores, a client may be helped to identify specific types of occupations he/she might explore further, based on the consistency of his/her interests with those of satisfied workers in those jobs. A computer-generated analysis of the profile assists counselors in pointing out patterns of high and low interests to the respondent.
As part of the profile, a respondent usually will obtain a three-point code, reflecting the occupational types with which his/her interests were most similar. These types are ordered according to level of similarity of interests. For example, a respondent with an "ISE" profile, would have an overall pattern of interests most consistent with the investigative type of occupations, followed by the social type, and the enterprising type.
Consistent with Holland's theory, a typical SCII profile will reveal that a respondent's interests falls along three adjacent types. However, this type of profile does not always occur. Some respondents obtain atypical profiles (e.g., REA; CEI). Atypical codes usually describe a person who has many varied, and possibly incompatible, interests. These respondents may need help in deciding which of those interests are most important, or deciding how they might integrate their varied interests in selecting a career and accompanying lifestyle.
The direction is very clear that the results can give estimates of the interest and preference of the participants and it is a good tool for them as a reference to choose their career path according to their interest and preference. Participants can find their interests and values from the Strong Interest Inventory.
Scoring Procedures/Software:
Responses to the SII are recorded on an optical scan form. The inventory cannot be hand-scored; it must be sent to the publisher's scoring service for electronic scoring.
Computer softwares such as SPSS, Professional Statistics (6.0) and (Version 5.06) enables the participants to score assessments, report results, and store and export data with ease and convenience. It can generate results accurately and efficiently, reports results, and stores information for 30 different assessment instruments from Pearson Assessments.
To score assessments, participants can also simply administer the test online, or or key-enter tests and get immediate results. To report results, choose from detailed narrative analysis to streamlined graphical profiles. You can even generate Progress reports at no extra charge for many assessments. Assessment results and other related information can be organized, stored, and regenerated in a variety of ways to meet your specific needs. Data can also be exported to other software applications for editing or creating your own database for outcome analysis.
Qualified therapists or clinicians are always required to handle and interpret the results of the Strong Interest Inventory. Strong Interpretive report is made by a qualified therapist to giver interpretation of the careers according to the test taker’s interest in each scale. It is an in-depth, personalized account of the results on the Strong TM Interest Inventory. The Report provides insights on overall patterns of interests that the test taker can explore. It can guide the test taker what they should do after viewing the results of the test. He/she should explore the occupations or take more different type of career tests. Then, they may be able to try to work as close as what they are interested and develop skills and knowledge in that area. E-consultation is provided to answer any questions and explanations for any problems along with the package purchased
SII was reviewed by Campbell and Hansen in 1981, 1985 and 1994 finally to enhance the face validity and also update the types of occupation and interest as the society and environment are changing with time. Therefore, SII is very up-to-date and can predict the future career successfully.
Technical Evaluation
Standardization
Strong Interest Inventory was updated in 1992 and 1993. More than 55,000 people in 50 occupations completed a research version of the 1994 Strong Interest Inventory during 1992 and 1993. It administered in 50 occupations (48 female-male paired samples, 2 single-gender samples). Median sample size for these criterion groups was 250, with fewer than 200 respondents in 8 groups. General Reference Sample (GRS) consists of random samples of 200 from 90 criterion group samples. Resulting GRS consists of 18,591 (9,467 female, 9,484 male) employed adults were selected on the basis of a set of criteria including job satisfaction, job experience, success, typicality of job description, and age with at least 3 years of job incumbency. The women in the sample averaged 13.8 years of experience in their occupation, and the men averaged 18.2 years. In most of the occupational samples, no more than 1 % or 2% of the respondents described performing duties atypical of their occupation. The average age of the women and men in the sample were 40.5 years and 44.6 years respectively. Of the total general reference sample of 18,591 people, 18,789 reported their ethnicity. Of these individuals, 1,424 (7.6%) were non-Caucasian: 378(2.0%) were African American, 363 (1. 9%) were Asian American, 349 (1. 9%) were Latino(a) or Hispanic American, 80 (0. 4%) were Native American, and 254 (1. 4%) were of other ethnicity. Across the 50 occupations in the general reference sample, 26 had 5% to 10% ethnic minority representation, 9 had more than 10% ethnic minority representation, and 15 had less than 5% ethnic minority representation. Within occupations, the highest ethnic minority representations were for translators (26. 7%), child care providers (20. 3%), and flight attendants (19. 5%); the lowest were for farmers (2. 1%), veterinarians (2. 3%), and accountants (2. 3%).
General Reference Scale (GRS) was used to calculate General Occupational Theme and Basic Interest Scales standard scores and to identify items differentiating occupational criterion groups for use in Occupational Scales calculation.
Reliability
Cronback alphas for General Occupational Theme (GOT), Basic Interest Scales (BIS) and Personal Style Scales (PSS) were calculated using the GRS. Four samples were used to demonstrate stability. The first sample of included 191 employed adults who were retested following 3- to 6- month interval. The second sample included 84 college students retested after a 1-month interval. The third sample and the fourth sample included 79 and 87 college students respectively enrolled in career development classes retested after 3-month intervals.
Alpha reliability estimates for General Occupational Themes were from 0.90 to 0.94. The General Occupational Themes test-retest reliability coefficient is from 0.74 to 0.92 with median retest coefficients of 0.89, 0.86, 0.82 and 0.83 for the four samples respectively. Alpha coefficients for the Basic Interest Scales were in the range of 0.74 to 0.94 with a median of 0.87. Basic Interest Scales retest reliability coefficients were in the 0.66 to 0.94 range with median retest coefficients of 0.86, 0.85, 0.80 and 0.83 for the four samples. Occupational Scales retest reliability coefficients were from 0.66 to 0.96. Median retest coefficients for the four samples were 0.90, 0.87, 0.85 and 0.84. For the Personal Style Scales, the alpha coefficients were 0.91 for Work Style, 0.86 for Learning Environment, 0.86 for Leadership, and 0.78 for Risk Taking/Adventure. Median retest reliability coefficients were 0.90, 0.86, 0.87 and 0.87 for the four samples.
Reliability properties for Strong Interest Inventory scales are impressive and the stability was highest for the employed adults. Stability was more than satisfactory for the groups of college students enrolled in career development classes.
Validity
Concurrent validity
There are two forms reported for the General Occupational Themes. The first form included 15 highest ranking and 15 lowest occupational groups listed for each General Occupational Theme. Predictable patterns were apparent. For example, auto mechanics and carpenters had highest Realistic GOT results; childcare providers and public relation directors had the lowest scores. The second form was that educational majors were determined for 16, 694 of the GRS respondents. Mean GOT profiles for each educational major group were consistent with theoretical expectations. Same method was used to document concurrent validity of the 25 Basic Interest Scales. Highest and lowest ranking occupations on each BIS were consistent with expectations. No direct evidence for predictive validity of the applied arts, culinary arts, data management, and computer activities BIS that were added in 1994. Concurrent validity of Occupational Scales was evaluated by calculating the Tilton Overlap (the percentage of OS scores in occupational criterion group matched by scores in the GRS distribution). Low overlap indicates criterion group is highly distinct from GRS. Lowest overlap percentage was 15% for male medical illustrator that indicates interest profile of this occupational group most distinct from GRS profile. Highest overlap was 61% for female small business owners (interest profile of this occupational group overlaps considerably with modal GRS interest profile). Median overlap for OSs was 36% that indicates a difference of almost 2 standard deviations in the OS means of criterion groups and GRS. OSs represent the unique interest profiles of distinct occupational groups. Mean GOT results of each OS criterion group also followed predicted pattern. Moderate-to-excellent hit rate of approximately 65% between OSs and subsequent occupational selections. Evidence constitutes strong support for predictive validity of OSs. Concurrent validity of PSSs addressed with method used for GOTs and BISs. PSS score distributions of various occupational and educational major groups were in predicted direction.
Differential Validity
SII developers took multifaceted approach to dealing with fact men and women are different in their responses to interest inventories. The first one is the standard scores for men and women on GOTs and BISs calculated using the means of the combined female and male GRS. Standard scored graphed on box-and-whisker graph distribution of the sex of the respondent. Female respondent may have a Realistic GOT score lower than male average, her score may appear higher than average on the female distribution. The second one is box-and-whisker graph distributions of both genders provided for each GOT, BIS and PSS. Respondents were able to examine how her or his results compare to norms of same and other gender. The third one is the scores calculated on the 102 OSs for which both male and female samples available. Respondents were able to compare similarity of their interests to those of both men and women in each of these occupations. The forth one is that OSs results based on same-gender groups are graphed on Strong Profile. Profile provides maximal information to respondent, but graphic presentation is focused on same-gender results. The fifth one is that GOT, BIS and OS results presented in the Snapshot compared to persons of same gender. This approach to reporting and presenting SII results acknowledges gender difference in interest test results yet empowers the counseling dyad to choose comparison groups when interpreting test results.
Strength and Weakness
The Strong Interest Inventory is the oldest and most researched interest test. It is easy to use and easy to understand. It also matches a person’s interest with various careers and occupations. It acts as an important tool as a source of information for educational planning. It provides both empirical and homogenous interest scale results in an attractive Profile. GOTs represent Holland’s hexagonal model better than other popular measures. There is no significant difference in the structures of female and male GOTs. Circular order of the 6 GOTs (R-I-A-S-E-C) holds for Caucasian, African, American, Asian American, African American, and Latino/Hispanic women and men. Administrative indices enable counselor to assess profile validity and provide insight into conflicting or confusing results. Guide provides extensive technical information and valuable suggestions for general interpretation of the Strong as well as for use with women, minority members and disabled individuals.
Every test has both strength and weakness. The criterion group data for 62 (29%) of the 211 OSs were collected more than 20 years ago (these may not adequately represent modal interest of contemporary job incumbents). Thus there is a need for updating of the criterion groups. Racial and ethnic group members were not adequately represented in the 1994 GRS. Discussion of predictive validity for the GOTs is limited. Greater effort should have been taken to summarize available evidence regarding predictive power of the GOTs. Also, manual does not specify the response percentages of those comprising the occupational criterion groups. No evidence was presented to describe how typical respondents were in comparison to all members of each occupational group.
Review:
A study (Donnay & Borgen, 1996) reviewed the validity of the Strong Interest Inventory with racial and ethnic groups in United Stated. The results provided strong support for the concurrent criterion-related validity of the 1994 SII with college-educated African American, Asian American, Caucasian American, Hispanic American, and Native American employed individuals who were satisfied with their current occupational outcomes. The generalizability of these results is limited, however, by the high educational level of the racial-ethnic groups in this sample.
Another study (Lattimore & Borgen, 1999) reviewed and quantified the capacity of the content (non-occupational) scales of the 1994 Strong Interest Inventory, as predictor sets, to predict occupational group membership. The results support the concurrent validity of the 35 content (non-occupational) scales of the Strong. In the meantime, the results of this study suggest that it is possible to accurately predict exact occupational group membership from the Strong, even when the occupational scales are excluded. Moreover, the content (non-occupational) scales may do so with greater parsimony and simplicity than the occupational scales, although this is an issue for future research. Continued investigations comparing the differential uses of the four types of scales on the Strong (i. e. , occupational scales, basic interest scales, general occupational themes, and personal style scales) are still needed to understand better the subtle ways that the inventory can be used with individuals to assist vocational choice.
Reference
Campbell, D. P., & Hansen, J. C. (1981). Manual for the SVIB-SCII (3rd ed.). Standford, CA: Standford University Press
Donnay, A. C., & Borgen, F. H. (1996). Journal of Counseling Psychology. 43 (3), pp. 275-291
Lattimore, R. R., & Journal of Counseling Psychology. 46 (2), pp. 185-195
Strong, E. K. (1927). Vocational Interest Blank. Standford, CA: Standford University Press