To estimate tration, insur-
be too in-
that passes
about 1/20
reasonable
18. Parent opinion, part 2 Let's revisit the school system
described in Exercise 17. Four new sampling strategies
have been proposed to help the PTA determine whether
parents favor requiring elementary students to pass a test
in order to be promoted to the next grade. For each, indi-
cate what kind of sampling strategy is involved and what
(if any) biases might result.
a) Run a poll on the local TV news, asking people to dial
one of two phone numbers to indicate whether they
favor or oppose the plan.
b) Hold a PTA meeting at each of the 20 elementary
schools, and tally the opinions expressed by those who
attend the meetings.
Duld be
d in each
nounced
ation.