2 Sample T Test menu Use a 2 Sample T Test if you want to compare two groups of scores which are not linked in any way It is an independent or between samples test 2 Select Basic Statistics

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2 Sample T Test menu Use a 2 Sample T Test if you want to compare two groups of scores which are not linked in any way It is an independent or between samples test 2 Select Basic Statistics Powered By Docstoc
					                             2-Sample T-Test (menu)


                                                         Use a 2-Sample T-Test
                                                         if you want to compare
                                                           two groups of scores
                                                         which are not linked in
                                                             any way. It is an
                                                        independent or between
                                                              samples test.


2. Select Basic Statistics
                                                        1. You can enter the
- 2-Sample t from the Stat
                                                      data in two ways: either
           menu
                                                       put each variable in a
                                                      different column (shown
                                                        here), or put both the
                                                      variables stacked in one
                                                       column with a second
                                                         column containing
                                                      subscripts or codes to
                                                      mark which group each
                                                       data point belongs to.
              2-Sample T-Test (dialog box 1: for data in two columns)


                       Note: This page is for data in two columns
                                                                3a. If your data is in
                                                                 different columns,
                                                                  click once on the
                                                                 white circle beside
                                                                  the ‘Samples in
                                                                Different Columns’
                                                                        option.
                                                                For data in one column
                                                                see next page.




 4a. Enter one variable into each of
these boxes by clicking on them and
then choosing a variable form the list
                 2-Sample T-Test (Dialog box 1: for data in one column)


                    Note: This page is for data in one column

                                                                  3b. Select the
                                                                ‘Samples in One
                                                                 Column’ option.

4b. Enter the variables by                                         If your data is in the
clicking on the white box                                          same column, make
   next to ‘Samples’ and                                              sure you have a
  then double-clicking on                                            second column of
 the name of the column                                           subscripts so that you
    containing your data                                            can identify which
     points. Enter your                                            condition each data
 subscripts by clicking on                                           point belongs to.
      the box next to
   ‘Subscripts’ and then
double-click on the name
of the column containing
your subscripts or codes.
                             2-Sample T-Test (Dialog box 2)

                                                                    5. If you want to
                                                                  perform a two-tailed
                                                                 test (recommended),
                                                                 choose not equal. If
                                                                  you want to perform
6. Choose the confidence level.                                     a one-tailed test,
     95 is commonly used.                                        choose whether you
                                                                  expect your sample
                                                                 mean to be less than
                                                                   or greater than the
                                                                   normal population
                                                                          mean.


 7. Click this box if you want to assume
                                                                   8. Click here if
   equal variances. This gives the test
                                                                    you want to
   more power, but also increases the
                                                 9. Click ‘OK’        generate
  likelihood of an error if the variances
                                                                    graphs. See
        aren’t equal. If in doubt, use
                                                                     next slide.
Descriptive Statistics to check that the
       variances of your groups are
   approximately equal; or carry out a
     Homogeneity of Variance test.
               2-Sample T-Test (Dialog box 3: Graphs)
                                          10. Select which graphs you want
                                             Minitab to perform. Do this by
                                         clicking once on the box next to the
                                         option. Once you have selected the
                                         option, a tick will appear in the box




11. Click OK
          2-Sample T-Test (output)
                                 The results will be printed in
                                     the session window




                                           Degrees of Freedom
                                            will be printed here




The T-Statistic will be      The P-Value will
    printed here             be printed here
2-Sample T-Test (Graph output)


                  Any graphs will also be printed
                      in a separate window




                                     The red lines on
                                   the dotplot indicate
                                    the means of the
                                   different conditions.