# Mean/Dispersion Tests - Form

Database Error - AddRecord

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.