A confidence statement based on a probability sample says, "One can be 95 percent confident that between 72 percent and 78 percent of all adult Americans believe that the country needs a national health-care system." The phrase "95 percent confident" means that:
A) if one took many samples, about 95 percent of the resulting intervals would contain the true value.
B) the sampling frame lists 95 percent of all American adults.
C) 95 percent of the sample agreed that Americans need a national health-care system.
D) the margin of error covers 95 percent of all responses in the population.

Question

Quizplus · Accepted Answer

The phrase "95 percent confident" refers to the level of confidence associated with the interval estimate provided. Specifically, it means that if we were to take many random samples from the population, about 95 percent of the resulting intervals that we construct using the same method would contain the true population value. This is also known as the level of significance or alpha level, which is typically set at 0.05. So, the correct answer is A.

A Confidence Statement Based on a Probability Sample Says, "One