Now assume that the sample standard deviation is SS = 480 and repeat the hypothesis test. t-critical = t = Rejection of the null hypothesis; there is a significant treatment effect. Rejection of the null hypothesis; there is not a significant treatment effect. Failure to reject the null hypothesis; there is not a significant treatment effect. Failure to reject the null hypothesis; there is a significant treatment effect. Explain how sample variability influences the likelihood of finding a significant mean difference. Low sample variability the likelihood of rejecting the null hypothesis if the null hypothesis is false