Question

Use an ANOVA to determine if there is a difference in mean weights between diets. Assume that all of the assumptions are met to perform the procedure. α = 0.01.use data set "chickweight" and use R

Answer 1

Null and Alternate hypothesis are

Ho : There is no difference in mean weights between diets

Ha : There is a difference in mean weights between diets

R-code

data(ChickWeight)
anova(lm(weight ~ Diet, ChickWeight))

Output

ANOVA table

Analysis of Variance Table

Response: weight
           Df  Sum Sq Mean Sq F value    Pr(>F)    
Diet        3  155863   51954   10.81 6.433e-07 ***
Residuals 574 2758693    4806                      

Conclusion :

From the ANOVA table output, we can see that the p-value (Pr (>F) = 6.433e-07) is very low

p-value < 0.05, hence we reject the null hypothesis

Thus, at 5% level of significance, we can say that there is enough statistical evidence to conclude that

there is a difference in mean weights between diets