Question

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. 25 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.) Pregnant nonvegetarians 185 189 187 181 Pregnant vegetarians 171 174 186 171 150 125 1 89 179 Nonpregnant vegetarians 139 172 198 177 163 153 176 207 210 139 174 184 160 How many degrees of freedom for the Between Groups calculation? How many degrees of freedom for the Within Groups calculation? F= Critical value of F= (use alpha = 0.05) Should you reject the null hypothesis?

Answer 1

The statistical software output for this problem is:

Analysis of Variance results: Data stored in separate columns. Column statistics Mean Std. Dev. Std. Error Columnn PN 8 184.25 21.835423 7.719988 PV 11 169.36364 18.57026 5.599144 NV 167 20.405882 8.3306662 6 ANOVA table F-Stat P-value Source DF SS MS Columns 2 1366.1145 683.05727 1.6945403 0.2068 Error 22 8868.0455 403.09298 Total 24 10234.16 CO

Hence,

Between Groups degrees of freedom = 2

Within Groups degrees of freedom = 22

F = 1.6945

Critical value = 3.4434

Should you reject? No