T-Test for Single Means

Select t-test, single sample on the Basic Statistics and Tables dialog box - Quick tab to display the T-Test for Single Means dialog box, which contains three tabs: Quick, Advanced, and Options. Use the options on these tabs to perform t-tests for single means.

Variables

  1. Click this button to display a variable selection dialog box.
  2. Select the variables to be analyzed.

    Summary

Click this button to compute the t-tests for single means and display the results in a spreadsheet.

The detail and formatting of the results depends on the selections made on the Options tab.

Cancel

Click this button to close the dialog box without performing an analysis and return to the Basic Statistics and Tables dialog box.

Options

Click this button to display the Options menu.

By Group

Click this button to display the By Group specification dialog box.

Select Cases

  1. Click this button to display the Analysis/Graph Case Selection Conditions dialog box.
  2. Use the options to create conditions for which cases will be included (or excluded) in the current analysis. More information is available in the case selection conditions overview and syntax summary.

    W

  3. Click the W (weight) button to display the Analysis/Graph Case Weights dialog box.
  4. Use these options to adjust the contribution of individual cases to the outcome of the current analysis by weighting those cases in proportion to the values of a selected variable.

    Weighted moments

Select this check box to specify that each observation contributes the weighting variable's value for that observation.

  • The weight values need not be integers.
  • This module can use fractional case weights in most computations.
  • Some other modules use case weights as integer case multipliers or frequency values.
  • This option is available only after you have defined a weight variable via the W option.

    DF = W-1 / N-1

When the Weighted moments check box is selected, some statistics related to the moments (such as standard deviations and variances, skewness, kurtosis) can be based on the sum of the weight values for the weighting variable (W-1), or on the number of (unweighted) observations (N-1).

The sums (and means), and sums of squares and cross products are always based on the weighted values of the respective observations. However, in computations requiring the degrees of freedom (such as standard deviation, t-test, etc.), the value for the degrees of freedom can either be computed as either of the following:

  • The sum of the weight values minus one
  • The number of observations minus one

Moment statistics (except for the mean) are based on

  • The sum of the weight values for the weighting variable when the W-1 option button is selected
  • The number of (unweighted) observations when the N-1 option button is selected

When the Weighted moments check box is selected, several graphics options are not available. For more information on options for using integer case weights, see Selecting a Weighting Variable.

MD deletion

  • When Casewise deletion of missing data is selected, Statistica ignores all cases that have missing data for any of the variables selected in the list.
  • When Pairwise deletion of missing data is selected, all valid data points are included in the analyses for the respective variables (resulting possibly in unequal valid N per variable).