With the test table pivoted so that assumptions are in the layer, the Equal variances assumed panel is displayed.

- The t column displays the observed t statistic for each sample, calculated as the ratio of the difference between sample means divided by the standard error of the difference.

- The df column displays degrees of freedom. For the independent samples t test, this equals the total number of cases in both samples minus 2.

- The column labeled Sig. (2-tailed) displays a probability from the t distribution with 498 degrees of freedom. The value listed is the probability of obtaining an absolute value greater than or equal to the observed t statistic, if the difference between the sample means is purely random.

- The Mean Difference is obtained by subtracting the sample mean for group 2 (the New Promotion group) from the sample mean for group 1.

- The 95% Confidence Interval of the Difference provides an estimate of the boundaries between which the true mean difference lies in 95% of all possible random samples of 500 cardholders.

Since the significance value of the test is less than 0.05, you can safely conclude that the average of 71.11 dollars more spent by cardholders receiving the reduced interest rate is not due to chance alone. The store will now consider extending the offer to all credit customers.