1. Measurement of Physical Activity
Subjective Measures

2. We also measure PA levels to:
• Evaluate current guidelines and trends S
• Set recommended levels of physical activity
• Investigate the relationship between physical activity and health
conditions
• Allow research to be conducted on large numbers of people,
allowing us to generalise about a wider population.

4. Reactivity
Reactivity is a phenomenon that occurs when individuals
alter their performance or behavior due to the awareness
that they are being observed
Example: Direct observation in a PE class (SOFIT)

5. Validity
In terms of assessment, validity refers to the extent to which a
test can allow accurate conclusions
Example: Does walking 10,000 steps a day equate to meeting
the national physical activity guidelines for adults?
http://www.10000steps.org.au/

6. So???
A tests validity (accuracy and correct representation of the
data) is highly dependent on the reactivity of test measure.

7. Social-desirability bias
• Social desirability bias is the tendency of
respondents to answer questions in a
manner that will be viewed favorably by
others.
• It can take the form of over-reporting
"good behavior" or under-reporting
"bad," or undesirable behavior.

8. Subjective Measures
Depend on our perceptions (what we
think/feel/value)
The are predominantly used for measurement of
populations

9. Measure of Assessment
Subjective
Objective
Self report (diaries/logs)
Heart-rate telemetry
Recall (surveys (SAPAC),
questionnaires (GPAQ, IPAQ),
proxy-reports)
Pedometers
Accelerometers
Direct Observation
(SOFIT, SOPLAY, BEACHES)

10. Self Report
Generally come in the form of a physical activity
diary or log
They record individual activities an person
performs in a day
They provide context, patterns of
behavior, intensity and duration

11. Self Report
Advantages
Disadvantages
Suitable for small groups or
individuals
Heavy subject burden (entries
completed throughout the day)
Usually easy to complete
Unreliable due to potential
misinterpretation or inaccurate
recording.
Able to provide detailed
information on context of an
activity (eg. Location, other
participants, subjects feelings)

12. Recall Surveys
Include the IPAQ and SAPAC
Less likely to influence behaviour and require
less effort compared to diaries/logs
5 – 15 minutes to complete (generally)
Provide basic data to assess the PA patterns in
large populations

13. Recall
Advantages
Inexpensive
Large sample size (measures large
populations)
Usually easy to complete
Able to collect a range of data
(qualitative and quantitative)
Disadvantages
Unreliable due to potential
misinterpretation of questions
Potential subjectivity or bias (eg.
Subjects may provide ‘socially
desirable’ responses’

14. Proxy Report
Either a diary/log or survey that is completed on
behalf of a respondent
Generally it will be a parent of a child or a
representative of an elderly person
“submitted by proxy”
Generally used when the respondent is not
cognitively capably of understanding or
remembering