a hypothesis test produces a t statistic of t=2.3. if the researcher is using a two tailed test with a=0.05 how large does the sample have to bw in order to reject the null hypothesis?

To evaluate the effect of a treatment, a sample of n = 8 is obtained from a population with a mean of μ = 40, and the treatment is administered to the individuals in the sample. After treatment, the sample mean is found to be M = 35. (Use the 4-step procedure to conduct the hypothesis test)  If the sample variance is s2 = 32, are the data sufficient to conclude that the treatment has a significant effect using a two-tailed test with α = .05? If the sample variance is s2 = 72, are the data sufficient to conclude that the treatment has a significant effect using a two-tailed test with α = .05? Comparing your answer for parts a and b, how does the variability of the scores in the sample influence the outcome of a hypothesis test?

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 sample of difference scores from a repeated-measures experiment has a mean of MD = 5 with a variance of s 2 = 64. If the sample size is n = 4, what is the correct decision if using a two-tailed test with alpha = .05? A. Accept the null hypothesis, there is a significant mean difference.    B. Accept the null hypothesis, there is not a significant mean difference.    C. Reject the null hypothesis, there is a significant mean difference.    D. Reject the null hypothesis, there is not a significant mean difference.

An independent consumer group published its finding that the lifetimes of electric bulbs manufactured by BIG Corporation are approximately normally distributed with a mean of 660 days and a variance of 15,625. BIG Corporation claims that the variance of its electric bulbs is less than 15,625. Suppose that we want to carry out a hypothesis test to see if BIG Corporation's claim is correct. State the null hypothesis H0 and the alternative hypothesis H1 that we would use for this test. H0:   H1: