Previous studies suggest that vegetarians may not receive en

Previous studies suggest that vegetarians may not receive enough zinc in their diets. As the zinc requirement is particularly important during pregnancy. researchers conducted a study to determine whether vegetarian pregnant women are at greater risk from low zinc levels than are nonvegetarian pregnant women. 22 women were monitored. The following table presents the zinc levels (ug/g) in the hair of three groups of women. (Data from J. C. King. Nutrition 34(1981): 1049-1055.) 125 How many degrees of freedom for the Within Groups calculation? How many degrees of freedom for the Between Groups calculation? Should you reject the null hypothesis?

Solution

One factor ANOVA

Mean

n

Std. Dev

190.7

7

12.89

preg nonveg

170.3

10

19.30

preg veg

169.8

5

21.49

nonpreg veg

176.7

22

19.78

Total

ANOVA table

Source

SS

   df

MS

F

   p-value

Treatment

2,022.44

2

1,011.222

3.10

.0683

Error

6,196.33

19

326.123

Total

8,218.77

21

Degrees of freedom between groups =2

Degrees of freedom within groups =19

F=3.10

Critical F= 3.52

Do not reject the null hypothesis

One factor ANOVA
	Mean	n	Std. Dev
	190.7	7	12.89	preg nonveg
	170.3	10	19.30	preg veg
	169.8	5	21.49	nonpreg veg
	176.7	22	19.78	Total
ANOVA table
Source	SS	df	MS	F	p-value
Treatment	2,022.44	2	1,011.222	3.10	.0683
Error	6,196.33	19	326.123
Total	8,218.77	21