We wish to use a one-way ANOVA model to compare the means of the four groups. Should we use a fixed effects or random-effects model, and why? 

Nutrition, Endocrinology

A study was performed to relate aspects of childhood diet to measurements of bone density in middle age (50- to 70-year-old) women [19]. The data in Table 12.46 were reported from a Norwegian study relating cod liver oil supplementation in childhood to bone mineral density (BMD) in the distal forearm.

Table 12.46: Mean BMD by cod liver oil intake during childhood

 

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Mean distal forearm BMD (g/cm?) (7,) Cod liver oil intake during childhood sd Never 0.435 0.058 267 Irregularly 0.424 0.061 695 Fall and winter 0.428 0.062 1655 Whole year 237 0.420 0.067 Overall mean () 0.427 2854