Variables/measurement/measurement characteristics

Question 1

Independent variables
- in intervention Studies
- in Prognosis Studies

Answer 1

• intervention studies: the presumed cause of a measured effect; Independent variable is the on manipulated
• Prognosis studies: the variable that is presumed to predict an outcome of interest; independent variable is the predictor variable

Question 2

Dependent variable

Answer 2

• the outcome of interest
• the variable that is hypothesized to be caused by the independent variable

Question 3

What are levels to independent variables

Answer 3

the number of forms the independent variable takes in a study

Question 4

Extraneous Variables

Answer 4

• confounds the relationship between the independent and dependent variables
• need to be anticipated and controlled for if possible
• these variables that could impact the result

Question 5

Discrete variables

Answer 5

• can assume only distinct values
• dichotomous: 2 values such as true/false
• polytomous: multiple values: scale of 1-10

Question 6

Continuous

Answer 6

Theoretically can assume infinitely finer degrees of measurement depending upon the instrument utilized

Question 7

what are the levels of measurement

Answer 7

1. nominal
2. ordinal
3. interval
4. ratio

Question 8

Nominal measurement

Answer 8

• classification w/o value placed on the category
• no ranking or order
• can use names or numerals
• ex: gender, religion, ethnicity

Question 9

Ordinal measurement

Answer 9

• classification with order but w/o equal intervals between levels
• can use numbers to label categories but cant do math
• Ex: weight bearing status, MMT scale (cannot find the difference between partial weight bearing and toe touch weight bearing/cannot say there are even amounts between levels)

Question 10

Interval measurement

Answer 10

• order and interval distance known
• origin is unknown/at no point where there is zero of the value
• can do addition and subtraction
• ex: temperature (there is no point where there is the absence of temperature)

Question 11

ratio measurement

Answer 11

• order, interval distance and origin known
• can add, subtract, multiply, and divide
• ex: height, weight, speed

Question 12

Reference standards of measurement and explain

Answer 12

1. norm referenced:
   - comparison of scores to previous test scores obtained from comparable subject
2. Criterion-referenced
   - comparison of scores to a previously established absolute standard

Question 13

What are the type of measurement reliablity

Answer 13

1. Instrument: test-retest, survey (internal consistency, parallel forms, split-half)
2. rater: intra-tester (within) or inter-tester (between 2 or more raters)

Question 14

Measurement validity

Answer 14

• the degree to which a measure captures what it is intended to measure
• reliablity is a necessary but no sufficient condition for validity

Question 15

Types of measurement validity

Answer 15

1. face validity
2. content validity
3. construct validity
4. criterion related validity

Question 16

Face validity

Answer 16

• does the measurement appear to asses what is intended
• addressed from the standpoint of the test and from the standpoint of the patient or family member

Question 17

Content validity

Answer 17

• the extent to which a measurement is judged to reflect the meaningful elements of a variable
• judged by content experts or people with experience with the variable
• evaluates how well and instrument covers all relevant parts of the construct it aims to measure

Question 18

Construct validity

Answer 18

• validity of abstract concepts that underlie the measure
• achieved via operational definitions, logical arguments, theoretical arguments and research evidence

Question 19

Criterion Validity

Answer 19

• extent to which one measure is systematically related other measures or outcomes
• requires direct comparison of index measure with a standard measure or with known outcome

Question 20

Forms of criterion validity

Answer 20

1. concurrent validity
2. predictive validity

Question 21

Concurrent validity

Answer 21

• the ability of an index measure to capture an outcome similar to that of another measure
• compare the index measure to the criterion measure, that was obtained at the same time

Question 22

predictive validity

Answer 22

• the ability of an index measure to predict a future outcome
• compare the index measure to the criterion measure that was obtained at a later point in time