Researchers investigated possible differences in gestation periods between two

breeds of horse. A sample of 20 Thoroughbred pregnancies from one farm had a

mean gestation period of 334.2 days, and a sample of 8 Standardbred pregnancies

from another farm had a mean gestation period of 336.2 days.

A person read this information and said "Looking at this data, we now know that

Standardbred horses have a longer gestation period than Thoroughbreds."

Which of the following statements are true? There may be more than one correct

statement; check all that are true.

a) This was an observational study of some nature, but still gives strong

evidence that the observed differences are caused by differences in the

breeds.

b) No meaningful conclusions can be drawn without much more information,

and the person's statement is unreasonable.

c) The biggest problem with the person's statement is that the two samples had

different sizes (20 vs 8), so we cannot properly compare the groups.

d) The values 334.2 and 336.2 are parameters.