Group averages are misleading when applied to individual pupils because of extensive overlapping in weight and height across grades¶

Claim · All claims
Evidence · 1 study · associational r1 · q2
Currency · newest study 1917 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q2 i? Individual variation within age-grade groups is so large that applying group averages to individual pupils would be misleading. → Stewart 1917

Evidence¶

Stewart 1917¶

Stewart, S. F. (1917). A study of physical growth and school standing of boys. The Journal of Educational Psychology. https://doi.org/10.1037/h0070804

q2 · i? · associational · r1

Descriptive comparison of individual records within the freshman group. Among thirteen-year-old freshmen the heaviest boy weighed 199 pounds and the lightest 73.9 pounds against a group average of 96.9 pounds; similar overlapping of eighth-grade boys is reported.

"of the freshman boys who were thirteen years of age, the heaviest boy weighed 199* pounds while the lightest weighed 73.9 pounds. The group average was 96.9 pounds."

Discussion¶

Related Claims¶

• Groups one year ahead of normal grade increase more rapidly in both weight and height than normal groups of the same age, with one exception — related
• Grades overlap massively in spelling: on average 20.8% of pupils reach or exceed the median of the next grade above — related
• Reading score distributions within A–F letter grades overlap heavily, so letter grades misrepresent the achievement of many individual students — related
• Physiologically accelerated children are mentally accelerated: height correlates with mental age +0.53 for 49 girls with age held constant — related
• Combining reading, writing and spelling scores still leaves immense grade overlap: on average 33.2% of pupils reach the next grade's range and 35.3% fall below their own grade's range — related
• Among boys of the same age, those one year above normal grade average both heavier and taller than boys of normal grade, and in some cases boys one year below normal also average heavier and taller — related
• Cross-sectional measurements of children of the same age may yield spurious growth facts because of great individual differences — possibly the same claim (merge candidate)
• Physiological age, as evidenced by the advent of pubescence or first menstruation, shows wide variations and low correlations with other traits — related
• Grouping pupils by mental age is not a reliable means of ensuring proper educational treatment — a narrower finding that bears on this claim