nutrition {emmeans} | R Documentation |
Nutrition data
Description
This observational dataset involves three factors, but where several factor combinations are missing. It is used as a case study in Milliken and Johnson, Chapter 17, p.202. (You may also find it in the second edition, p.278.)
Usage
nutrition
Format
A data frame with 107 observations and 4 variables:
age
a factor with levels
1
,2
,3
,4
. Mother's age group.group
a factor with levels
FoodStamps
,NoAid
. Whether or not the family receives food stamp assistance.race
a factor with levels
Black
,Hispanic
,White
. Mother's race.gain
a numeric vector (the response variable). Gain score (posttest minus pretest) on knowledge of nutrition.
Details
A survey was conducted by home economists “to study how much lower-socioeconomic-level mothers knew about nutrition and to judge the effect of a training program designed to increase their knowledge of nutrition.” This is a messy dataset with several empty cells.
Source
Milliken, G. A. and Johnson, D. E. (1984) Analysis of Messy Data – Volume I: Designed Experiments. Van Nostrand, ISBN 0-534-02713-7.
Examples
nutr.aov <- aov(gain ~ (group + age + race)^2, data = nutrition)
# Summarize predictions for age group 3
nutr.emm <- emmeans(nutr.aov, ~ race * group, at = list(age="3"))
emmip(nutr.emm, race ~ group)
# Hispanics seem exceptional; but this doesn't test out due to very sparse data
pairs(nutr.emm, by = "group")
pairs(nutr.emm, by = "race")