T-Tests

Performs a one- or two-sample t-test. The menu carries out validity checks. If any sample has fewer than 6 values, a warning is given that the sample size is too small and the test may not be valid. Also, in the two-sample (unpaired) case, an F-test for equality of variance is carried out and a warning printed if there is evidence of unequal variances. For a two-sample unpaired t-test you can also choose to calculate the probability using a random permutation test.

Test

Specifies the test to be carried out: One-sample, Two-sample (unpaired), or Two-sample (paired).

Data Arrangement

For a Two-sample (unpaired) test the data can be supplied either as a pair of variates or as a single variate with a factor defining the groups.

Two Sets

The samples must be supplied as two separate variates, whose names should be entered as Data Set 1 and Data Set 2.

One Set with Groups

The data must be supplied in one variate, specified as the Data Set. Membership of the two samples is then indicated by a factor whose name should be entered in Groups.

Confidence Limit

Allows you to control the limit for the calculation of a confidence interval. The limit is expressed as a percentage and must be in the range 0-100

Type of Test

Allows you to choose either a one-sided or two-sided t-test.

Available Data

List variates and factors that can be used to supply the data sets and/or groups. The contents may change as you move from one input field to another, so that appropriate types of data structure are listed. Double-click on a name to copy it into the current input filed; alternatively you can enter the name directly using the keyboard.