Suppose you conduct a hypothesis test about a population mean when the standard deviation is known (a "z test") by calculating a z statistic and determining whether to reject the null hypothesis. Assume that your z statistic is a positive value and that you will reject the null hypothesis when z is very large. Listed below are possible changes to the study design or to the results of the study. Determine whether the likelihood of rejecting the null hypothesis increases, decreases, or stays the same for each of these changes. Change in Study Design or Results The z statistic
A switch from using a one-tailed test to a two-tailed test ?
A decrease in the population standard deviation ?
An increase in the significance level (such as using a = .05 instead of α = .01) ?
An increase in the sample size (n) ?

Suppose you fail to reject the null hypothesis. Then, the results of your study are .