The Mean/Dispersion Tests routine performs numerous one and two-sample tests of means and variances. Both independent and dependent tests are available. Confidence intervals are displayed for all means, standard deviations, and correlation.
Clicking the 
button sends output to the Mean/Dispersion Tests Output Form.
Menu
- File provides the ability to Print the Graph and Text, or return to the Main Form.
- Edit allows Editing Output Text by cutting, copying, pasting, and undoing entry, and provides the abililty to Copy the Graph to the Windows Clipboard.
- View: Provides the ability to enlarge the Form size for easier viewing.
- Help provides access to this Website.
Mean/Dispersion Tests Speed Buttons
- These buttons provide quick access to the following tasks.
Returns to the Main Form.
Opens a Data File.
Displays the Data Editor.
Displays the T/F Output Form.
Copies text to the clipboard
Enlarges/Reduces Form size for easier viewing.
Brings up the Main Form.
Pastes text from the clipboard.
Brings up this Help file.
Hides the form.
Group1 Title
The title for group 1 will be displayed here. This is changed when variables are selected from a data file.
Group2 Title
The title for group 2 will be displayed here. This is changed when variables are selected from a data file.
_
X1
Enter the sample mean of the first group here.
s1
Enter the sample standard deviation (or variance) of the first group here.
n1
Enter the sample size for the first group here.
_
X2
Enter the sample mean of the second group here.
When this is blank for a single sample test, only the confidence interval will be displayed.
s2
For two-sample tests, enter the sample standard deviation (or variance) of the second group here.
For single sample tests, enter the hypothesized value here. If this value is zero, only the confidence interval will be displayed.
n2
Enter the sample size for the second group here.
Confidence Level
The confidence level used in calculations may be entered here. The value is expressed in percent. The confidence level may be changed by selecting and typing in the level, or by using a drop-down selection.
Test Selection
Select One-Sample Mean Test, One-Sample Variance Test, Two-sample Independent Tests, or Two-sample Dependent Tests.
Variance Selection
Select whether variances are standard deviations are to be entered.
Hypotheses for Means
Select the desired Null Hypothesis for the means tests. A non-directional or directional hypothesis may be selected.
Hypotheses for Variances
Select the desired Null Hypothesis for the variance tests. A non-directional or directional hypothesis may be selected.
Degrees of freedom Calculations
This option is available only for Single Mean tests and Two-Sample Independent tests.
This selects one of three modes of analysis:
- Standard performs standard calculations to determine degrees of freedom
- df from MSE requires the degrees of freedom be entered (df(s)) that were used to generate a standard deviation, typically from another analysis such as an ANOVA.
- Sigma Known assumes sigma is known and performs z-tests instead of t-tests.
Decimal Place Change
Changes the number of decimal places, from 0 to 9. Change may be made by selecting and typing in the number, or by using the incrementing buttons.
Action Button
Performs calculations and displays output.
File Data Button
Allows selection of variables found in the data editor. This button brings up the Mean/Dispersion Tests - Data Select Form.
Reset Button
When this button is clicked, all input is reset to the default settings.