Chapter 9, Problem 9.4LB

Under what circumstances is the t statistic used instead of the Z score for a hypothesis test?

If a hypothesis is rejected at significance level α = 0.01, is it possible that the hypothesis is not rejected if the same test was done at significance level α = 0.05 (with everything else staying the same)?

As a result of dog breeding for certain physical traits, many dog breeds have changed in the last 100 years. A dog breeder wants to measure the effects of breeding on the face length of the boxer breed using a hypothesis test. Suppose that the dog breeder has face length measurements (in inches) from a random sample of 40 female boxer dogs taken in 1915 and a random sample of 40 female boxer dogs taken in 2015. Which type of hypothesis test should the breeder use? Reference: Elegans, C. 100 Years of Breed Improvement. 2012. Dog Behavior Science. Retrieved from: https://dogbehaviorscience.wordpress.com/2012/09/29/100-years-of-breed-improvement  Test for one population proportion  Test for one population mean  Test for a difference in two population proportions  Test for a difference in two population means

According to the most recent General Social Survey, 70% of adults watch TV nightly. A researcher believes that the proportion of college students who watch TV nightly is less than this. To test this claim the research samples 400 college students and finds that 276 watch TV nightly. At the 0.05 level of significance does this data provide evidence to suggest that the proportion of college students who watch TV nightly is less than 70%? Select the correct hypothesis test for this problem:

Under what circumstances is a t statistic used instead of a z-score for a hypothesis test?     Justin wants to know whether a commonly prescribed drug does improve the attention span of students with attention deficit disorder (ADD). He knows that the mean attention span for students with ADD who are not taking the drug is 2.3 minutes long. His sample of 12 students taking the drug yielded a mean of 4.6 minutes. Justin can find no information regarding σx , so he calculated s2x =1.96. Identify the independent and dependent variables. In a sentence, state the null hypothesis being tested. c. Using symbols, state the null and alternative hypotheses

Under what circumstances is a t statistic used instead of a z-score for a hypothesis test?     Justin wants to know whether a commonly prescribed drug does improve the attention span of students with attention deficit disorder (ADD). He knows that the mean attention span for students with ADD who are not taking the drug is 2.3 minutes long. His sample of 12 students taking the drug yielded a mean of 4.6 minutes. Justin can find no information regarding σx , so he calculated s2x =1.96. Determine the critical region using a one-tailed test with alpha = .05. Conduct the hypothesis test (Do the math and compare the t-critical and t-obtained values). State your conclusions in terms of H0 (Should you reject the H0 or fail to reject/accept the H0). Based on your analysis, is there a relationship between the drug and attention span?

A research report describing the results from a repeated-measures t test states that “t(22) = 1.71,  p > .05.” From this report, what was the outcome of the hypothesis test?

need part B

Illustrate the null hypothesis for a correlated t test?