3. Determine the P-value, 4. Make a decision about the hypothesis
Q: According to the National Institute for Occupational Safety and Health, job stress poses a major threat to the health of workers. A national survey of restaurant employees found that 75% said that job stress had a negative mpact on their personal lives. A sample of 100 employees of a restaurant chain finds that 68 answer "Yes" when asked: "Does job stress have a negative impact on your personal life?" Is this good reaon to think that the proportion of all employees of this chain who would say "Yes" differs from the national proportion, p(0)=.75? Use a 5% level of significance.
1. State the Null Hypothesis and Alternative Hypothesis, 2. Determine the test statistic?
1. because the question says "differs" you have a two tail test
H0: p = 0.70 vs H1: p ≠ 0.70
2. Because of the large sample size we can assume normality and use the Z statistic for the hypothesis test
3. the p-value is the probability of observing a sample in bigger disagreement with the null hypothesis H0, than we saw in this case.
Find the test statistic
Z = (p - p0) / Sqrt[p0 * (1-p0) / n]
Z = 0.68 - 0.75 / Sqrt[ 0.7*0.3/100]
Z = -1.5275252
the p-value = P[ Z %26lt; -1.53] + P[ Z %26gt; 1.53] = 0.063 + 0.063 = 0.126
4. since the p-value = 0.126 is greater than the significance level we conclude that H0, the null hypothesis, is plausible. Note that we cannot conclude that the null if true, only that it is plausible.
Reply:Use Normal Distribution
np=u, var=npq
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I remember statistics. It was actually one of the most useful forms of mathematics that I still use today. Now that is not to say the calculus does not still have its uses. I enjoyed the theories behind calc but, I do not use it everyday. Yet, I digress. When I was taking satistics, I used spread sheets on the computer to help quicken my calculations and organize my raw data.
ReplyDeleteFor a student this is an easy task. A company trying to organize raw data will be too large to just be able to use a spread sheet, survey software will be needed. Survery Software helps organize, and its easy visual interface will take the stress off the person taking the survey allowing them to answer more honestly. So don't turn people into survey monkeys.