Data are from King et al. (1981), Effect of vegetarianism on the zinc 
status of pregnant women," The American Journal of Clinical Nutrituion, 
34: 1049-1055.

Data are zinc levels (in micro-g per g) in the hair of women on three
different diet types. group = 1 corresponds to pregnant non-vegetarians.
group = 2 corresponds to pregnant vegetarians. group = 3 corresponds
to non-pregnant vegetarians. Zinc levels are particularly crucial during
pregnancy, and the fear is that pregnant vegetarians in particular do not
get enough.

These data were reproduced in:

Ramsey and Schafer (1997). The Statistical Sleuth: A course in methods
of data analysis, Duxbury Press.