PT526 - Week 3
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44 terms
Terms | Definitions |
|---|---|
PICO(T) | population intervention comparison outcome (TIME) |
The role of the Independent variable | predictor, antecedent |
The role of the DEPENDENT variable | outcome, consequent |
Research hypothesis | expresses researcher true expectation of results |
Statistical or Null hypothesis | implies no change |
Validity | degree to which a useful (meaningful) interpretation can be inferred from a measurement |
Construct Validity | conceptual (theoretical) basis for using a measurement to make an inferred interpretation; evidence for construct validity is through logical argumentation based on theoretical and research evidence |
Content validity | a form of validity that deals with the extent to which a measurement is judged to reflect the meaningful elements of a construct and not any extraneous elements |
The three forms of Criterion-based (criterion-related) validity | concurrent validity, predictive validity, and prescriptive validity |
The common element of the three forms of criterion-based validity | with each form, correctness of an inferred interpretation can be tested by comparing a measurement with either a different measurement or data obtained by other forms of testing |
Concurrent validity | form of criterion based validity in which an inferred interpretation is justified by comparing a measurement with supporting evidence that was obtained at approximately the same time as the measurement being validated |
Predictive validity | form of criterion based validity in which an inferred interpretation is justified by comparing a measurement with supporting evidence that was obtained at a later point in time; examines the justification of using a measurement to say something about future events or conditions |
Prescriptive validity | a form of criterion based validity in which the inferred interpretation of a measurement is the determination of the form of treatment a person is to receive; is justified based on the successful outcome of the chosen treatment |
Face validity | assumption of validity of a measurement instrument based on its appearance as a reasonable measure of a given variable |
If valid... | must be reliable |
If reliable... | may or may not be valid |
Evidence in support of construct validity | 1. Known groups method 2. Multi-trait multi-method matrix (trait and method) 3. Factor analysis |
Convergent validity | scores of similar people will be similar |
Divergent validity | scores of different people will be different |
Whats very important for functional assessment tools? | content validityfor example: SF36 assessment of Health-Related Quality of Life Usually determined by a panel of experts |
Content validity is inextricably linked to | construct validity |
what differentiates concurrent validity from predictive? | two measurements are taken at the same time |
the gold standard in measurement parlance | measurement beyond reproach - one that everyone agrees is valid, and against which other measures can be validated |
With predictive validity, measuring something now will | predict an outcome later |
PT Example of predictive validity | screening tests |
Prescriptive validity is similar to.. | predictive but now guides intervention ex: sensory organization test |
Issues related to criterion based validity | norm vs criterion referencing |
Problems with norm referencing | 1. no one person is normal 2. how big a deviation from normal is clinically relevant? |
Whats criterion referencing and whats the problem? | choose an absolute, against which all are measured; Problem: who chose the criterion? |
Sensitivity | ability of a test to obtain a positive test when the condition is present; a sensitive test rarely misses a positive diagnosis (if they got it, they test positive) |
Specificity | ability of a test to obtain a negative test when the condition is absent; a specific test rarely misses a negative diagnosis (if they dont got it, they test negative) |
Sensitivity equation = | Number of people with true positives / number of people who should be positive a / (a + c) |
Specificity | Number of people with true negatives / number of people who should be negative d / (b + d) |
predictive value of a positive test = | number of people with true positives / number of people who test positive |
predictive value of a negative test = | number of people with true negatives / number of people who test negative |
predictive values are dependent on | prevalence of the disease; if disease is more prevalent, you will get a higher positive predictive value |
sensitivity and specificity are not affected as much by | prevalence |
Receiver operating characteristics allows you to | choose the best operating point; the best balance |
Change Score | difference between the outcome (after) score and the initial (before) score |
Four issues affecting the validity of change scores | 1. level of measurement 2. reliability 3. stability 4. linearity |
Level of measurement | ordinal scales- for evaluation and talk about improvementratio data - interval is usually considered pretty good as well |
Linearity | refers to the fact that the difference between 60 and 70% isnt the same as the difference between 88 and 98% but both are increases by 10. Ceiling and floor effects come into play here as well |
Ceiling effects example | Berg - those old people with no balance |
Floor effects examples | SAT scores |
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