Now down here I want to make sure this radio button for hypothesis test is selected. And I'm going to do the same thing for the second sample.
I put the total number from that group in here. And since we're looking at fatality rate, we want to look at the number of deaths. Try to think of it as you're looking for the part of the whole that you're trying to examine. I know it's really weird to consider that people dying is considered success, but try not to think of it that way. So for that first sample, it's going to be 31. The number of successes is the part of the whole that we're looking at. That's the same order that they're listed here. Again, we're asked to make the first sample the group that's not wearing seatbelts and the second sample the group that is wearing seatbelts. And they're listed here in the problem statement. Here in the options window, I’m going to list my summary stats. So for that, I'm going to go to Stat –> Proportion Stats –> Two Sample –> With Summary. We just need the functionality of StatCrunch. We don't need any data for the data table. And because there's no icon to click on, it's often a good idea for you to keep a copy of StatCrunch open, just in case you need to access it like you do here but you don't have any data. Notice there's no icon or any data that you have to dump into StatCrunch. And to do that I'm going to pull up StatCrunch. Now we're asked to identify the test statistic. So p2 (the group wearing the seatbelts) will be less than p1. The group wearing seatbelts - if the claim is that the seat belts are going to be effective in reducing fatalities, and that means the group wearing the seatbelts is going to have a lower proportion of deaths than the group not wearing a seat belt. So we can adopt the claim as our alternative hypothesis. That's great, because now we see that there's no semblance of equality that's being made in the claim it's just one is greater than the other. This is the same order in which they're listed here in the problem statement. And it says here that we're supposed to consider the group not wearing seatbelts as the first sample and the group wearing seatbelts as the second sample. OK, so we have two groups: One group who was not wearing seatbelts, the other group who was wearing a seatbelts. What is the claim that's being made? Back here in the problem statement, we can see we're testing the claim that seatbelts are effective in reducing fatalities. To determine the correct alternative hypothesis, we need to go and look at the claim. So we're having to choose between answer option B, D, and E, because all of these answer options have the null hypothesis as a statement of equality.
So right off the bat, we know that answer option A, C, and F are incorrect. But which of these answer options is the right one? Well, let's figure that out.īy definition, the null hypothesis is always a statement of equality. We're doing a hypothesis test on proportions, and so our parameter in our hypothesis is going to be proportions, which we see here. OK, Part A asks us to test the claim using a hypothesis test, and the first part of the hypothesis test is forming our null and alternative hypotheses.
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