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Stability of M-ABC-2-measured motor functioning in early childhood: Evidence from a large prospective cohort
Scott Veldhuizen1, Chloe Bedard2, Sara King-Dowling3
1Nicotine Dependence Service, Centre for Addiction and Mental Health, Toronto, ON, Canada.
Insights
Improvements in children's motor skills may be illusory due to regression towards the mean (RTM). This study shows that apparent gains in motor functioning are consistent with measurement error, not true development.
Area of Science:
- Child Development
- Motor Skills Assessment
- Statistical Analysis
Background:
- Previous studies suggest children with poor motor functioning improve over time.
- Existing research often overlooks regression towards the mean (RTM), a statistical phenomenon.
- Accurate assessment of motor skill stability is crucial for understanding child development.
Purpose of the Study:
- To examine measurement stability in motor functioning among preschool-aged children.
- To differentiate true developmental changes from statistical artifacts like RTM.
- To re-evaluate the interpretation of motor skill improvements in research.
Main Methods:
- Administered the Movement Assessment Battery for Children 2nd Edition annually to 589 children (aged 4-5 years).
- Analyzed score agreement between Year 1 and Year 2 using Pearson correlation.
- Regressed follow-up scores on baseline scores, controlling for covariates and simulating RTM.
Main Results:
- The mean score for children with poor coordination increased from 5.6 to 7.2.
- Year 1 and Year 2 scores showed a correlation of r=0.66, aligning with predicted RTM.
- Observed improvements closely matched expected RTM, indicating stability was not significantly affected by time between assessments.
Conclusions:
- Apparent improvements in children's motor functioning may be attributed to measurement error and RTM.
- The stability of motor functioning might be higher than previously reported.
- RTM must be considered to avoid overestimating functional gains in research.
Aim:
Some studies have reported that children with poor motor functioning tend to improve over time. However, much existing research does not account for regression towards the mean (RTM). Here, we examine measurement stability among 589 children aged 4-5 years.
Method:
We administered the Movement Assessment Battery for Children 2nd Edition annually to 269 children initially scoring above and 252 at or below the 16th percentile. We measured agreement between year 1 and year 2 standard scores using Pearson correlation and derived expected regression towards the mean (RTM). We then regressed follow-up on baseline scores, controlling for relative age, sex, and exact interval between assessments. Finally, we performed a small illustrative simulation.
Outcomes And Results:
The mean score in the poor-coordination group rose from 5.6 (SD = 1.5) to 7.2 (SD = 2.8). Year 1 and year 2 scores were correlated at r = 0.66, corresponding to predicted RTM in the MI group of 1.56, close to the observed change of 1.57. Degree of change was not associated with time between assessments.
Interpretation:
Observed improvements in motor functioning were consistent with measurement error. The stability of motor functioning may be greater than it appears from past research, and reported functional improvements in some studies may be illusory. WHAT THIS PAPER ADDS?
