Chicken Feed

Chicken farming is a multi-billion dollar industry, and any methods that increase the growth rate of young chicks can reduce consumer costs while increasing company profits, possibly by millions of dollars. An experiment was conducted to measure and compare the effectiveness of various feed supplements on the growth rate of chickens. Newly hatched chicks were randomly allocated into six groups, and each group was given a different feed supplement. Below are some summary statistics from this data set along with box plots showing the distribution of weights by feed type.

chickenData = read.csv('http://people.hsc.edu/faculty-staff/blins/spring17/math222/data/chickwts.csv')
boxplot(weight~feed,data=chickenData,col='gray')

1. Make an ANOVA table for this data. Does it look like the differences in the weights of the chicks are statistically significant?

2. Do the groups each appear to have a normal distribution? How big are the sample sizes of the the groups?

3. What are the standard deviations of the groups? Are they fairly close to each other? Use the aggregate() function.