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Experimental design: generalization
A good experiment allows its results to be generalized
As a potential buyer of cat food, what would be important to me is whether my
cat would prefer MoggyScoff to other leading brands. I am not interested in what
other people's cats like.
However, I could reasonably assume that my cat was not very different from
other cats. So if a sufficient number of other people's cats preferred
MoggyScoff to other brands, I would be reasonably happy to buy it myself.
The problem with questioning ten people at a supermarket checkout is that the
result, while it may be perfectly true of these ten peoples' cats, probably does not allow us to
make any claim about other peoples' cats.
We say that the finding is not generalizable or does not
generalize. An experiment that does generalize allows us to make inferences
about the results that would be found if the experiment were carried out on
a large population.
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