Feeding fish. In the midwestern United States, a large
aquaculture industry raises largemouth bass. Researchers
wanted to know whether the fish would grow better if
fed a natural diet of fathead minnows or an artificial diet
of food pellets. They stocked six ponds with bass finger-
lings weighing about 8 grams. For one year, the fish in
three of the ponds were fed minnows, and the others
were fed the commercially prepared pellets. The fish
were then harvested, weighed, and measured. The bass
fed a natural food source had a higher average length
(19.6 cm) and weight (95.9 g) than those fed the commer-
cial fish food (17.3 cm and 72.0 g, respectively). The re-
searchers reported P-values for differences in both meas-
urements to be less than 0.001.
a) Explain to someone who has not studied Statistics
what the P-values mean here.
b) What advice should the researchers give the people
who raise largemouth bass?
c) If that advice turns out to be incorrect, what type of
error occurred?