For a random sample of Canadians, 60% indicate approval of the prime minister’s performance. A similar poll a month later has a favorable rating of 57%. A 99%

confidence interval for the change in the population proportions is (−0.07, 0.01). Explain why

(a) there may have been no change in support,

(b) if a decrease in support occurred, it may have been fairly important, whereas if an increase in support occurred, it was probably so small as to be substantively unimportant.