Table 3

Summary of analytical approaches’ (including descriptor, mathematical transformation and statistical model) strengths and limitations in relation to closure, collinearity, relation-shape assumptions and interpretation relative to public health guidelines

DescriptorCoDA transformStatistical modellingRisk of closure?*Risk of collinearity?Handles closure?Handles collinearity?Relationship assumptionsAllow investigation of longitudinal associations (eg, Cox regression)Interpretation relative to guidelines? (eg, 150 min/week of MVPA)
Average acceleration No Linear NoNoNANALinearYesNo
Time-use descriptors No Linear YesYesNoNoLinearYesYes
Yes Linear YesYesYesIn part†Log-linearYesYes
No ISO YesYesYesNoLinearYesYes
No MPA YesYesNoNoLinearNot at the momentYes
Yes MPA YesYesYesYesLog-linearNot at the momentYes
Intensity spectrum No Linear YesYesNoNoLinearYesYes‡
Yes Linear YesYesYesIn part†Log-linearYesYes‡
No ISO YesYesYesNoLinearYesYes‡
No MPA YesYesNoNoLinearNot at the momentYes‡
Yes MPA YesYesYesYesLog-linearNot at the momentYes‡
Intensity gradient No Linear NoNoNANALinearYesNo
No FDA NoNoNANAFewer assumptions than other modelsYesYes§
MX metrics No Linear YesYesNoNoLinearYesYes‡
No MPA YesYesNoYesLinearNot at the momentYes‡
Other acceleration functions No FDA NoNoNANAFewer assumptions than other modelsYesYes§
  • *Closure refers to whether a certain descriptor is a specific part of the daily time constraint (ie, it is measured in time per day).

  • †Indicates that it solves the collinearity due to the closure, but collinearity can still exist across the CoDA-transformed variables.

  • ‡Indicates that the interpretation is made through a post-hoc application of validated cut-points to identify the PA intensity (eg, MVPA).

  • §Indicates that more work is needed on the interpretation of functional data analysis, an example can be found elsewhere.39

  • CoDA, compositional data analysis; FDA, functional data analysis; ISO, isotemporal substitution models; MPA, multivariate pattern analysis; MVPA, moderate-to-vigorous PA; MX, acceleration above which a person’s most active X minutes/time are spent; NA, not applicable; PA, physical activity.