For large sample cases, in a two-tailed test of the difference between two population means (significance level = 5%), the decision rule is: A)Reject the null hypothesis if the test statistic, z_stat, is either less than −1.96 or greater than +1.96. B)Reject the null hypothesis if the test statistic, z_stat, is either greater than −1.96 or less than +1.96. C)Reject the null hypothesis if the p-value is greater than .05. D)Reject the null hypothesis if the test statistic, t_stat, is either less than −1.022 or greater than +1.022.

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For a two-tailed test with a significance level of 5%, the critical z-values are -1.96 and +1.96. If the test statistic falls outside of this range (either below -1.96 or above +1.96), the null hypothesis is rejected. This is based on the standard normal distribution where approximately 95% of the values lie within 1.96 standard deviations of the mean.

For Large Sample Cases, in a Two-Tailed Test of the Difference