Measurement

Question 0

Define: continuous variable

Answer 0

Quantitative variable that an theoretically take on values along a continuum

Question 1

Define: variable

Answer 1

Characteristic that can be manipulated or observed and can take on difference values (quantitatively or qualitatively)

Question 2

Define: discrete variable

Answer 2

A variable that can only be measured in separate units and that can not be measured in intervals of less than 1

Question 3

Define: dichotomous variable

Answer 3

A nominal variable having only two categories such as yes/no, male/female

Question 4

Define: construct

Answer 4

Concepts that represent nonobservable behaviors or events; invented names for abstract variable that cannot be seen directly example: intelligence, strength, health

Question 5

Define: nominal measurement

Answer 5

Classifies variables into mutually exclusive categories (red, yellow, blue)

Question 6

Define: ordinal measurement

Answer 6

Rank-ordered measurement
Unequal intervals between categories
Greater than, less than
(Manual muscle testing)

Question 7

Define: interval measurement

Answer 7

Rank-ordered
Equal intervals between categories
No true zero
(Temperature, range of motion)

Question 8

Define: ratio measurement

Answer 8

Highest level of measurement
Rank ordered
Equal intervals between categories
True zero

Question 9

Define: Reliability

Answer 9

The extent to which a measurement is consistent and free from error

Question 10

Define: systematic error

Answer 10

Predictable and directional, consistent from trial to trial

Question 11

Define: random error

Answer 11

Measurement error due to chances, bidirectional

Question 12

Define: validity

Answer 12

The extents to which an instrument measures what it is intended to measure

Question 13

Define: sensitivity

Answer 13

Test’s ability to obtain a true positive

Question 14

Define: specificity

Answer 14

Test’s ability to obtain a true negative

Question 15

Define: positive predictive value

Answer 15

Probability that a person who tests positively actually has the condition.

Question 16

Define: negative predictive value

Answer 16

Probability that a person who tests negatively does not have the condition.

Question 17

Define: Positive likelihood ratio

Answer 17

True positive rate divided by false positive rate.

Sensitivity/(1-specificity)

Question 18

Define: negative likelihood ratio

Answer 18

False negative rate divided my true negative rate.

(1-sensitivity)/specificity

Question 19

Define: measurement

Answer 19

Process of assigning numerals to variables to represent quantities of characteristics according to certain rules

Question 20

Sources of measurement error (3)

Answer 20

Individual taking the measurement
Measuring instrument
Variability of the characteristic being measured

Question 21

3 types of variables

Answer 21

Continuous
Discrete
Dichotomous

Question 22

4 levels of measurement

Answer 22

Nominal
Ordinal
Interval
Ratio

Question 23

Reliability coefficient

Answer 23

Ratio of true score variance to the total variance

T/(T+E)

.75 is good
>.90 is usually required for clinical decision-making

Question 24

Types of reliability (4)

Answer 24

Test-retest Rater Internal consistency Alternate forms

Question 25

Test-retest reliability

Answer 25

Consistency of measurement from time 1 to time 2

Question 26

Intrarater reliability

Answer 26

How consistently one individual measures a characteristic across toe or more trials

Question 27

Interrater reliability

Answer 27

Consistency of measurement between two or more raters measuring the same characteristic

Question 28

Internal consistency (type of reliability)

Answer 28

Extent to which multiple items agree when measure aspects of the same characteristic i.e. a pain survey may have many questions, higher consistency=higher reliability

Question 29

Alternate forms (type of reliability)

Answer 29

Consistency between two instruments designed to measure the same characteristic

Question 30

Validity vs reliability

Answer 30

To be valid, a measure MUST be reliable | Not all reliable measurements are valid.

Question 31

Types of measurement validity (6)

Answer 31

``` Face validity Content validity Concurrent validity Predictive validity Prescriptive validity Construct validity ```

Question 32

Face validity

Answer 32

An instrument "appears" to measure what it's purported to measure; least rigorous form of validity

Question 33

Content validity

Answer 33

Extent to which a measurement generalizes to a theoretical universal score. Are all parts of the whole defined? i.e. A pain questionnaire has more content validity than an 11pt scale

Question 34

Concurrent validity

Answer 34

Variable measured with instrument of interest and "good standard" concurrently.

Question 35

Predictive validity

Answer 35

Degree to whic a measurement is predictive of some future score

Question 36

Prescriptive validity

Answer 36

Degree to which a measurement can be used as a basis for selecting an appropriate intervention i.e. Balance score dictates certain ambulatory device

Question 37

Construct validity

Answer 37

Ability of an instrument to measure an abstract construct; not directly observable