Use this dialog to select the output generated by a randomization test of the difference between two groups, and the options used in the test.
Specifies which items are displayed in the Output window or the Graphics window.
|Summary and estimates||A summary, estimates and the randomization test probability. Additional information is displayed when the t-test method is used which includes the lower and upper confidence limits.|
|Histogram of samples||A histogram of the randomization distribution of the statistic with the observed statistic marked on the graph.|
Type of test
Lets you choose either a one- or two-sided t-test. A two-sided test looks for differences either side of 0, whereas a one-sided test checks whether the mean is greater than or less than the given mean.
Estimate of variance for t-test
This option is only available when the two-sample t-test method is selected. For a two-sample t-test you can choose which method is used for estimate of variances for the test statistic.
|Automatic||Uses a pooled estimate unless there is evidence of unequal variances.|
|Pooled||Always uses a pooled estimate of the standard deviation for the test, i.e. a common standard deviation that is formed from the average variance over the two groups.|
|Separate||Estimate the standard deviation for the test using separate variances.|
Confidence limits (%)
This option is only available when the two-sample t-test method is selected. This lets you control the limits for the calculation of the confidence interval for the t-test. The limit is expressed as a percentage in the range 0-100.
Seed for randomization
This gives a seed to initialize the random number generation used for resampling the data. Using zero initializes this from the computer’s clock: specifying a non-zero value gives a repeatable analysis.