See the published version of this preprint at BMC Medical Research Methodology.
This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
A new preprint design is coming!
We have improved readability, clarity, accessibility, and opportunities for engagement.
Research article
License:
This work is licensed under a CC BY 4.0 License. Read Full License
BACKGROUND Measuring physical activity and sedentary behavior accurately remains a challenge. When describing the uncertainty of mean values or when making group comparisons, minimising Standard Error of the Mean (SEM) is important. The sample size and the number of repeated observations within each subject influence the size of the SEM. In this study we have investigated how different combinations of sample sizes and repeated observations influence the magnitude of the SEM.
METHODS A convenience sample were asked to wear an accelerometer for 28 consecutive days. Based on the within and between subject variances the SEM for the different combinations of sample sizes and number of monitored days was calculated.
RESULTS Fifty subjects (67% women, mean±SD age 41±19 years) were included. The analyses showed, independent of which intensity level of physical activity or how measurement protocol was designed, that the largest reductions in SEM was seen as the sample size were increased. The same magnitude in reductions to SEM was not seen for increasing the number of repeated measurement days within each subject.
CONCLUSION The most effective way of reducing the SEM is to have a large sample size rather than a long observation period within each individual. Even though the importance of reducing the SEM to increase the power of detecting differences between groups is well-known it is seldom considered when developing appropriate protocols for accelerometer based research. Therefore the results presented herein serves to highlight this fact and have the potential to stimulate debate and challenge current best practice recommendations of accelerometer based physical activity research.
Keywords
physical activity, sedentary behavior, accelerometer
Figure 1
Figure 2
This is a list of supplementary files associated with this preprint. Click to download.
Loading...
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Published
View the published article at BMC Medical Research Methodology.
Version 3
Posted 19 May, 2020
No community comments so far
Editorial decision: Accept
On 21 May, 2020
Review #1 received
Received 20 May, 2020
Review #2 received
Received 19 May, 2020
Reviewer #2 agreed
On 13 May, 2020
Reviewers invited
Invitations sent on 12 May, 2020
Reviewer #1 agreed
On 12 May, 2020
Editor assigned
On 07 May, 2020
Editor invited
On 06 May, 2020
Submission checks complete
On 01 Jul, 2019
No comments provided
Editorial decision: Major revision
On 08 Apr, 2020
Review #2 received
Received 25 Mar, 2020
Reviewer #2 agreed
On 17 Mar, 2020
Review #1 received
Received 12 Feb, 2020
Reviewer #1 agreed
On 30 Jan, 2020
Reviewers invited
Invitations sent on 10 Sep, 2019
Editor assigned
On 19 Jul, 2019
Submission checks complete
On 18 Jul, 2019
Editor invited
On 18 Jul, 2019
No comments provided
Editorial decision: Major revision
On 02 Jul, 2019
Submission checks complete
On 01 Jul, 2019
Editor assigned
On 28 Jun, 2019
Editor invited
On 27 Jun, 2019
First submitted
On 26 Jun, 2019
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Physical Medicine & Rehab
Learn more about our company.
A new preprint design is coming!
We have improved readability, clarity, accessibility, and opportunities for engagement.
See the published version of this preprint at BMC Medical Research Methodology.
This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research article
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Published
View the published article at BMC Medical Research Methodology.
Version 3
Posted 19 May, 2020
No community comments so far
Editorial decision: Accept
On 21 May, 2020
Review #1 received
Received 20 May, 2020
Review #2 received
Received 19 May, 2020
Reviewer #2 agreed
On 13 May, 2020
Reviewers invited
Invitations sent on 12 May, 2020
Reviewer #1 agreed
On 12 May, 2020
Editor assigned
On 07 May, 2020
Editor invited
On 06 May, 2020
Submission checks complete
On 01 Jul, 2019
No comments provided
Editorial decision: Major revision
On 08 Apr, 2020
Review #2 received
Received 25 Mar, 2020
Reviewer #2 agreed
On 17 Mar, 2020
Review #1 received
Received 12 Feb, 2020
Reviewer #1 agreed
On 30 Jan, 2020
Reviewers invited
Invitations sent on 10 Sep, 2019
Editor assigned
On 19 Jul, 2019
Submission checks complete
On 18 Jul, 2019
Editor invited
On 18 Jul, 2019
No comments provided
Editorial decision: Major revision
On 02 Jul, 2019
Submission checks complete
On 01 Jul, 2019
Editor assigned
On 28 Jun, 2019
Editor invited
On 27 Jun, 2019
First submitted
On 26 Jun, 2019
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Physical Medicine & Rehab
License:
This work is licensed under a CC BY 4.0 License. Read Full License
View the published article at BMC Medical Research Methodology.
BACKGROUND Measuring physical activity and sedentary behavior accurately remains a challenge. When describing the uncertainty of mean values or when making group comparisons, minimising Standard Error of the Mean (SEM) is important. The sample size and the number of repeated observations within each subject influence the size of the SEM. In this study we have investigated how different combinations of sample sizes and repeated observations influence the magnitude of the SEM.
METHODS A convenience sample were asked to wear an accelerometer for 28 consecutive days. Based on the within and between subject variances the SEM for the different combinations of sample sizes and number of monitored days was calculated.
RESULTS Fifty subjects (67% women, mean±SD age 41±19 years) were included. The analyses showed, independent of which intensity level of physical activity or how measurement protocol was designed, that the largest reductions in SEM was seen as the sample size were increased. The same magnitude in reductions to SEM was not seen for increasing the number of repeated measurement days within each subject.
CONCLUSION The most effective way of reducing the SEM is to have a large sample size rather than a long observation period within each individual. Even though the importance of reducing the SEM to increase the power of detecting differences between groups is well-known it is seldom considered when developing appropriate protocols for accelerometer based research. Therefore the results presented herein serves to highlight this fact and have the potential to stimulate debate and challenge current best practice recommendations of accelerometer based physical activity research.
Figure 1
Figure 2
This is a list of supplementary files associated with this preprint. Click to download.
Loading...