Factors that influence a hypothesis test with the t statistic Suppose you conduct a hypothesis test about a population mean when the standard deviation is unknown by calculating a t statistic and determining whether to reject the null hypothesis. Assume that your t statistic is a positive value and that you will reject the null hypothesis when t is very large. For each of the potential changes to the components of your study design or the results listed below, determine the change to the t statistic, and then select "Increases," "Decreases," or "Stays the same" from the dropdown menu in the right-hand column. Change in Study Design or Results The t statistic A decrease in the significance level (such as using α = .01 instead of α = .05) A decrease in the sample variance (s²) A decrease in the obtained difference (M – μ) A switch from using a one-tailed test to a two-tailed test