When data from a set of evaluations (e.g., AMPS, School AMPS, or ESI observations or ACQ-OP/ACQ-SI interviews) are entered into the computer and analyzed with specialized Rasch analysis computer programs, the computer program calibrates the elements of each facet along the same common linear continuum. In this process, logistic transformation procedures are used to convert ordinal raw data (e.g., scores of 1, 2, 3 or 4) into linear (equal interval) calibrations. These calibrations are mathematical estimates of where on the linear continuum the element (i.e., each item, each task/social exchange, each rater, each person) most likely is located. In the case of the AMPS, ACQ-OP, School AMPS, ESI, and ACQ-SI, items are calibrated for their difficulties, tasks/social exchanges are calibrated in terms of their challenges, and raters are calibrated in terms of their severities. With the AMPS, School AMPS, and ESI, people are calibrated in terms of their degree of quality of occupational performance. With the AMPS, quality of occupational performance is calibrated along two separate linear continua or scales, ADL motor ability and ADL process ability. Likewise, for the School AMPS, there are two linear continua, school motor and school process. The ESI has only one scale, quality of social interaction. The ACQ-OP and ACQ-SI have one discrepancy scale each.
The rater severity calibration is the estimated location of that rater on the same continuum of increasing (a) ADL motor or ADL process ability, (b) school motor or school process ability, or (c) quality of social interaction, with the rater calibration values representing a continuum of severity from more lenient to more strict raters of a person’s quality of occupational performance. The final estimate of each rater severity calibration is based on a logistic transformation of the sum of the item ratings that each rater assigned to a common set of calibration cases scored during an AMPS, School AMPS, or ESI training course. Raters who overall assign lower ratings have proportionally lower summed raw total scores, and are calibrated as more severe raters.
With the AMPS, School AMPS, and the ESI, the item difficulty calibration is the estimated location of each ADL, school, or social interaction item (i.e., motor, process, and social interaction skills) on the continuum of increasing quality of ADL, schoolwork, or social interaction, respectively, ranging from easy to hard items. The final estimate of each ADL, school, and social interaction item difficulty calibration is based on a logistic transformation of all the ratings in the respective database that have been given to each ADL, school, or social interaction item. Items more often given low ratings have proportionally lower summed raw total scores, and are calibrated as more difficult ADL, school, or social interaction skills.
The task/social exchange challenge calibration of the AMPS, School AMPS, and ESI is the estimated location of each task/social exchange on the same continuum of (a) increasing ADL motor or ADL process ability, (b) increasing school motor and school process ability, or (c) increasing quality of social interaction, ranging from very easy to much harder task/social exchange challenge. The final estimate of each task/social exchange challenge calibration is based on a logistic transformation of the sum of all the item ratings that were assigned to each task/social exchange in the respective database when people performed that task/social exchange. Tasks/social exchanges more often given low ratings have proportionally lower summed raw total scores, and are calibrated as more challenging tasks/social exchanges.
The person measure (person calibration) is the estimated location of that person on the continuum of increasing (a) ADL motor or ADL process ability, (b) school motor or school process ability, or (c) quality of social interaction. The person measure represents how skilled the person was when he or she performed AMPS, School AMPS, or ESI tasks/social exchanges. The final estimate of each person’s measure is based on a logistic transformation of the sum of the item ratings (i.e., ADL motor, ADL process, school motor, school process, social interaction) that the rater assigned when he or she scored that person. Unlike item, task/social exchange, and rater calibrations, however, person measures are adjusted (i.e., moved up or down along the common scale) to account for the challenges of the tasks/social exchanges the person performed and the severity of the rater who scored the person’s occupational performance.
Includes both the person who has been referred to occupational therapy and others who are close to that person and whose occupational performances have been impacted by the person and his or her occupational challenges (e.g., a person who has had a stroke and his or her spouse who now needs to care for the person, a student in a classroom and the teacher who will need to implement accommodations or modifications).
Pertains to a group of persons who have no other special relationship outside the fact that they may experience similar occupational challenges or concerns (e.g., a group of persons with dementia and their carers, a population of well older persons living in the community who may be at risk for developing occupational challenges, a governmental agency desiring advice on how to develop occupational opportunities for youth) (Fisher, 2009).
To be engaged in the action of performing of daily life tasks. Thus, occupation pertains to the person being engaged in doing something (e.g., getting dressed, playing cards, reading a book). Thus, occupation should not be confused with or referred to as the task the person will have done or plans to do (e.g., get dressed, play cards, read a book) (Fisher, 2006, 2009).
To engage a person in occupation and use that engagement as the foundation or method of evaluation and/or intervention—the person is engaged in the performance of a chosen daily life task that unfolds as it ordinarily does in the person’s life (Fisher, 2013; see also Pierce, 1998).
To adopt a professional stance or perspective—a world view of occupation and what it means to be an occupational being—where occupation is placed in the center and ensures that everything an occupational therapist does is linked to the core paradigm of occupational therapy (Fisher, 2013; see also Hooper, 2006; Nielson, 1998; Yerxa, 1998).
To focus one’s attention on occupation—to have occupation as the proximal (i.e., immediate) focus of the evaluation or the proximal intent of the intervention (Fisher, 2013; see also Letts, 2011).
“Discrete purposeful actions [that] can be discerned” (Kielhofner, 2008, p. 103); they are the smallest observable units of occupational performance — the goal-directed actions a person carries out one-by-one as he or she is engaged in naturalistic and relevant daily life task performances (Fisher, 2009; Fisher & Griswold, 2014). Performance skills include: motor skills, process skills, and social interaction skills.
Occupational performance skills (e.g., ADL process skills, school process skills) observed as a person (a) selects, interacts with, and uses task tools and materials; (b) carries out individual actions and steps; and (c) modifies performance when problems are encountered.
Rasch models of measurement are a family of models that are based on the idea of first conceptualizing a logical pattern of responses, and then collecting data to verify that the expectations are met. Because all Rasch measurement models are probabilistic, the expectations are based on assertions that acknowledge that not all people will always respond in exactly the same way. For example, the assertions of the simple Rasch model, where all items are scored dichotomously (e.g., pass or fail, agree or disagree), are that (a) items that are more difficult (e.g., preparing a complex meal) are more likely to be more difficult for all persons than are items that are less difficult (e.g., combing one’s hair), and (b) persons with more of the trait being evaluated (e.g., more ADL ability), are more likely to pass more difficult items than are persons with less of the trait.
Many-faceted Rasch models are an extension of the simple Rasch model because they include more than two facets. That is, the simple Rasch model considers (a) items that represent the trait or construct to be measured (e.g., the item of combing one’s hair represents the construct of ADL) and (b) persons who have more or less of the trait. In the simple Rasch model, items and persons are the facets — the simple Rasch model is thus a two-faceted model. In the case of the AMPS, School AMPS, and ESI, we have four facets: (a) items (motor, process, and social interaction performance skills) that vary in terms of how difficult they are to perform in a competent, skillful manner; (b) tasks (ADL tasks, schoolwork tasks, types of social exchanges) that vary in the challenge they offer to the person who performs them; (c) raters who vary in severity when they score the quality of the person’s occupational performance; and (d) people who vary in terms of their quality of occupational performance (ADL, schoolwork, social interaction).
For more information about the use of Rasch measurement methods to develop and validate the AMPS, we recommend reading Chapter 14 of the AMPS manual (Fisher & Merritt, 2012). The content of this chapter also provides important background information for understanding the basic concepts underlying the development of the School AMPS and the ESI. A copy of this chapter can be found here. More information about using Rasch analysis methods to calibrate items, tasks/social exchanges, raters, and persons is found above.
What a person will do or what it is that the person did do – the unit of action that will be done once the person is finished performing it (e.g., get dressed, play cards, read a book). People perform tasks, and when they are engaged in that task performance, we can observe occupation (e.g., we can observe the person as he or she is getting dressed, playing cards, reading a book) (Fisher, 2006, 2009).
Fisher, A. G. (2013). Occupation-centered, occupation-based, occupation-focused: Same, same or different? Scandinavian Journal of Occupational Therapy, 20, 162–173.
Fisher, A. G. (2009). Occupational Therapy Intervention Process Model: A model for planning and implementing top–down, client-centered, and occupation-based interventions. Ft. Collins, CO: Three Star Press.
Fisher, A. G. (2006). Overview of performance skills and client factors. In H. M. Pendleton, & W. Schultz-Krohn (Eds.), Pedretti’s occupational therapy: Practice skills for physical dysfunction (6th ed., pp. 372-402). St. Louis MO: Mosby Elsevier.
Fisher, A. G., & Griswold, L. A. (2014). Performance skills: Implementing performance analyses to evaluate quality of occupational performance. In B. B. Schell, G. Gillen, M. Scaffa, & E. Cohn (eds.), Willard & Spackman’s occupational therapy (12th ed.). Philadelphia: Lippincott Williams & Wilkins.
Fisher, A. G., & Merritt, B. K. (2012). Conceptualizing and developing the AMPS within a framework of modern objective measurement. In A. G. Fisher, & K. B. Jones, Assessment of Motor and Process Skills. Vol. 1: Development, Standardization, and Administration Manual (revised 7th ed.). Fort Collins, CO: Three Star Press.
Hooper, B. (2006). Beyond active learning: A case study of teaching practices in an occupation-centered curriculum. American Journal of Occupational Therapy, 60, 551–562.
Kielhofner, G. (2008). Model of Human Occupation: Theory and application (4th ed.). Baltimore: Wolters Kluwer | Lippincott Williams & Wilkins.
Letts, L. J. (2011). Muriel Driver Memorial Lecture 2011: Optimal positioning of occupational therapy. Canadian Journal of Occupational Therapy, 78, 209–217. doi: 10.2182/cjot.2011.78.4.2
Nielson, C. (1998). The issue is: How can the academic culture move toward occupation-centered education? American Journal of Occupational Therapy, 52, 386–387.
Pierce, D. (1998). The issue is: What is the source of occupation’s treatment power? American Journal of Occupational Therapy, 52, 490–491.
Yerxa, E. J. (1998). Occupation: The keystone of a curriculum for a self-defined profession. American Journal of Occupational Therapy, 52, 365–372.