2.6-Measurement Properties

Question 1

How is measurement used in Physiotherapy

Answer 1

• As a basis for prognosis, diagnosis and result evaluation
• Initial assessment
  -Outcome assessment

Question 2

Continuous Variable

Answer 2

-A variable along a scale within a defined range
-Examples: joint range, distance walked, time

Question 3

Discrete Variable

Answer 3

-Whole unit variables
-Examples: Heart rate, number of steps

Question 4

Dichotomous Variable

Answer 4

-Binary variable with a related context (qualitative)
-Example: Return to sport, survival

Question 5

Indirect vs direct variables

Answer 5

Indirect- Correlation to a characteristic representative of the variable (Temperature, heart rate)
Direct- Observational variable (Height, weight)

Question 6

Constructs (abstract variables)

Answer 6

Unobservable variables which are inferred based on relevant properties

(Abstract concepts-Motivation)
(Direct constructs- Temperature)

Limitation: Definition alters via discipline

Question 7

Nominal

Answer 7

-Categorical with no particular order
- Mutually exclusive (cannot assign multiple categories, lowest yield)
- Blood type, handedness, pregnancy

Question 8

Ordinal

Answer 8

-Ranked according to order in relation to a property
-Common in clinical assessment
-Non-quantitative relationship
-Sensation (Normal, impaired, absent)

Question 9

Interval

Answer 9

-Rank order characteristics along with interval distances and units
-Relative difference can be determined
-Numerical value that does not represent true nature of the variable
-Temperature (0 zero temperature is not absence of heat or cold)

Question 10

Ratio

Answer 10

-Empirical zero + interval scale
-Highest level of measurement
-Statistics can be applied
-Distance, age, time, weight, BP

Question 11

Reliability

Answer 11

The degree to which individuals can be distinguished from
each other despite measurement error

Question 12

Measurement error

Answer 12

he systematic and random error of an individual’s score that is
not attributed to true changes in the construct to be measured

Question 13

Construct validity

Answer 13

The extent to which scores of the outcome measure relate to
other measures in a manner that is consistent with theoretically
derived hypothesis concerning the concepts that are being
measured

Question 14

Criterion validity

Answer 14

The extent to which scores of the outcome measure relate to
the gold standard

Question 15

Responsiveness

Answer 15

The ability of an outcome measure to detect clinically important
changes over time

Question 16

Validity

Answer 16

A test must measure what it is ought to measure.

Question 17

Systematic errors

Answer 17

-Predictable
-Constant and biased
-Occur in one direction at all times (under estimation or over estimation)

Question 18

Random errors

Answer 18

-Non-predictable and due to uncontrollable factors such as fatigue, distraction and simple mistakes
-Error due to chance

Question 19

Sources of error for patients?

Answer 19

1. Cognitive impairment
2. Physical impairment (pain, anxiety, fear etc)
3. Lack of familiarity with procedure
4. Distracted by environment
5. Recovery or disease progression

Question 20

How to minimise systematic error?

Answer 20

1.Test at similar times of the day
2. Check comprehension
3. Provide familiarisation of task to reduce nervousness and increase confidence
4. Standardise environment
5. Quiet environment
6. Assessment of pain intensity prior to test
7. Consider number of reps to avoid fatigue

Question 21

Sources for error for clinicians

Answer 21

1. Skill at performing the measurement, Preparation, Motivation / interest, Procedure used
   2.Starting position
   3.Handling
2. Instructions
3. Data Collection (?standardized)

Question 22

How to minimise systematic error for clinicians?

Answer 22

1. Increase skill / competence of conducting / reading the measurement
2. Procedure used
3. Standardised starting position
4. Standardised handling / stabilisation
5. Standardised instructions
6. Standardised use of equipment
7. Standardised recording of results

Question 23

Sources of error in equipment?

Answer 23

1. Faulty Components
2. Poor Calibration
3. Variable Operating Conditions
4. Poor Alignment / set up
5. Requires Warm Up or Cool Down

Question 24

How to minimise equipment error?

Answer 24

1. Regular calibration / maintenance of equipment.
2. Standardised warm-up time.
3. Standardised operating conditions.
4. Use the same piece of equipment.

Question 25

Types of reliability?

Answer 25

1. Test-retest
2. Intra-rater
3. Inter-rater

Question 26

Test-retest reliability

Answer 26

To establish that an instrument is capable
of measuring a variable with consistency

Used where raters are not involved, such
as self-report questionnaires or in lab-
based assessments of equipment

Question 27

Intra-rater reliability

Answer 27

1. The stability of data recorded by one
   individual across two or more trials
2. Same assessor, same subjects and across 2 trials.

Question 28

Inter-rater reliability

Answer 28

1. The consistency of measurements
   between different clinicians when
   measuring the same subject(s)
2. Multiple measurers, same subjects, same trial fashion

Question 29

MCID- Minimal clinically important difference

Answer 29

is the smallest change that is
perceived to be beneficial by the
patient and would lead to a change in
management in the absence of
excessive side effects and costs

Question 30

Distribution based approaches:

Answer 30

Degree of change in groups of patients
Related to a distribution of scores
(differences in group means and variance within the distribution)
E.g. standard response mean (SRM)

Question 31

Anchor-based methods

Answer 31

Use external clinical criteria (anchor) to define clinical important
change
(e.g. a little better, a lot better, a little worse, a lot worse)