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 accelerationNoLinearNoNoNANALinearYesNo
Time-use descriptorsNoLinearYesYesNoNoLinearYesYes
YesLinearYesYesYesIn part†Log-linearYesYes
NoISOYesYesYesNoLinearYesYes
NoMPAYesYesNoNoLinearNot at the momentYes
YesMPAYesYesYesYesLog-linearNot at the momentYes
Intensity spectrumNoLinearYesYesNoNoLinearYesYes‡
YesLinearYesYesYesIn part†Log-linearYesYes‡
NoISOYesYesYesNoLinearYesYes‡
NoMPAYesYesNoNoLinearNot at the momentYes‡
YesMPAYesYesYesYesLog-linearNot at the momentYes‡
Intensity gradientNoLinearNoNoNANALinearYesNo
NoFDANoNoNANAFewer assumptions than other modelsYesYes§
MX metricsNoLinearYesYesNoNoLinearYesYes‡
NoMPAYesYesNoYesLinearNot at the momentYes‡
Other acceleration functionsNoFDANoNoNANAFewer 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.