Chapter 12 Flashcards
●An ordered system based on a series of questions or items, resulting in a score that represents the degree to which a respondent possesses a particular latent trait (attitude, value, or characteristic).
●Should be unidimensional, representing a single construct.
●Generic or related to specific patient groups.
Scale
●Total score is obtained by adding values across a set of items.
●Items on the scale are generally on an ordinal scale.
●All items contribute equally to the total score.
Summarize scales
Formats of summarize scales
Likert scales
Visual analog scales
Ordinal scale (e.g., disagree to agree)
●Range from low to high
•Odd number (1-5), with neutral point
•Even number (1-6) forces choice
Examples of likert scales
●Fixed at 100 mm (10 cm) in length
•Measured in mm but underlying measure is ordinal
●Anchors at extremes (best to worst)
●Frequently used to measure the intensity of pain from a patient’s perspective
●Also used to measure other constructs such as stress, anxiety, disability, fatigue, quality of life
Example of a visual analog scale
Variations of visual analog scales
Numeric rating scales
Faces rating scale
•Example: rating pain from 0 to 10
•An ordinal scale
Numeric rating scale
•Example: use of different faces to represent aspects of pain
•Developed for use in children but may be used with adults
Faces rating scale
●Items reflect increasing severity of the characteristic being measured
●Each item is dichotomous
●Total cumulative score based on the number of items the individual agrees with
●Maximum score is the number of items
●Different individuals with the same score should have the same level of ability
●Also known as Guttman scales
Cumulative scores
●Based on Item Response Theory
•Ranking of persons
•Hierarchy of items
Rasch analysis
Rasch analysis Uses
•Transformation of ordinal data into interval values
•Translation of scores across instruments
‒Ability level of respondent and difficulty of items are the same across instruments
True/False: with Rasch analysis Questionnaire items are expected to fit a model whereby item difficulty and person ability are consistent.
True
indicate how well difficulty and ability match.
Fit statistics
Item bias in fit to Rasch model for different groups, such as cultures, disorders, age.
Differential item functioning (DIF)
●Based on Item Response Theory
●Designed to adjust the difficulty of items to match the ability of the test taker
●Used for standardized testing
●Can be used to reduce the number of items administered with a health status questionnaire
Computer adaptive testing
