Diverging Paths: Longitudinal and Reciprocal Associations Between Two Fundamental Motor Skill Assessments in Preschoolers.

Only 72 of the 117 children were still in the study a year later. The children who dropped out were more likely to be older, to be Black, to come from households earning under $30,000 and to have higher screen time and higher physical activity at the start, so the one-year findings may not describe the group that began the study. The authors note flooding in the area before the second round moved some families, which they say may have made these losses not random. The two assessments were given a year apart with no information collected on what the children did in between, so nothing here shows one motor skill causing another, or that any particular activity changed the result. The authors themselves say the small amount of variation explained and the wide spread of scores at follow-up mean other factors they did not measure are likely to matter. Percentile scores compare each child with other children of the same age, and those other children improve over time. A child who stays the same will therefore fall in percentile, so a falling score is not the same as losing a skill. This is a secondary analysis of data collected for a different question, about childcare centre policies on physical activity and screen use, and only 72 children contributed to the one-year models.

Funded by the National Institute on Minority Health and Health Disparities of the National Institutes of Health (U54 MD 008602), with additional support from NIDDK (P30 DK072476 and T32DK064584) and from the National Institute of General Medical Sciences (U54 GM104940). No commercial funder is named. The authors state the content is solely their responsibility and does not necessarily represent the official views of the National Institutes of Health.

Do not read the falling scores as preschoolers losing motor skills. These are percentile scores, which compare each child with other children of the same age, and those others improve over the year, so a child who stays the same drops in percentile. Equally, the missing link between the two tests a year later does not prove they measure unrelated things: only 72 children were followed up, and the authors say low numbers, measurement error and differences in developmental timing may all have affected the result.