Select the best answer a simple random sample of 1200 adult...

Select the best answer A simple random sample of 1200 adult Americans is selected, and each person is asked the following question: “In light of the huge national deficit, should the government at this time spend additional money to establish a national system of health insurance?” Only 39% of those responding answered “Yes.” This survey (a) is reasonably accurate since it used a large simple random sample. (b) needs to be larger since only about 24 people were drawn from each state. (c) probably understates the percent of people who favor a system of national health insurance. (d) is very inaccurate but neither understates nor overstates the percent of people who favor a system of national health insurance. Since simple random sampling was used, it is unbiased. (e) probably overstates the percent of people who favor a system of national health insurance.

Transcript

00:06 A simple random sample of 1 ,200 adults were selected, and they were asked, in light of the huge national deficit, do you support national health insurance? 39 % responded, yes, they support national health insurance.

00:29 The question is, do we maybe have a bias in this survey? is this is the 39 % of their people that responded yes 39 % of the 1200 adults in our sample responded yes they do support the national health insurance is this an accurate number should it maybe really have been a little bit more could it have been less is there bias all right well let me mention a couple things the fact that we selected a simple random sample, this is a good thing.

01:11 You don't want voluntary response samples.

01:14 You don't want convenient samples.

01:16 You want simple random samples, where the people selected were just randomly selected.

01:22 So that's a good thing.

01:24 When you have simple random samples, that's a good way to try to avoid bias.

01:30 Now, the other thing you want to look for is a large sample size.

01:35 1 ,200 adults is a really good sample size.

01:40 So we have good things going here where we should be avoiding bias.

01:46 So at the moment, answer a looks good, where the 39 % of the adults in the sample responded, yes.

02:02 That should be reasonably accurate if we, because we have a simple random sample, because we have a large sample size, we're trying to avoid bias.

02:13 Normally we would say that 39 % that responded, yes, it should be accurate because we have a large sample size and we have a simple random sample.

02:23 So a looks pretty good because a says, you know, that the results are reasonably accurate.

02:29 But here's why i don't think a is going to be the answer.

02:32 I actually think c is going to be the answer and here's why.

02:36 I think we do have bias, even though we had a large sample size and we did conduct a simple random sampling.

02:44 I think we have bias because of the way the question in the survey was asked.

02:51 We led them...