Tutorial #5 - Using the StatWizard

The StatWizard is designed to serve several functions:

• It helps users select statistical procedures that are appropriate for their data.
   
• It provides a search facility to help locate specific statistics and tests.
   
• It contains a mechanism to apply one or more analyses to each level of a specified “BY” variable.

Each function is illustrated below.
 

Selecting Statistical Procedures Based on the Type of Data

1. If the STATGRAPHICS DataBook currently contains data, select File - Close - Close StatFolio from the main STATGRAPHICS menu to clear all data and analyses.
    
2. Select File - Open - Open Data Source from the main STATGRAPHICS menu.
    
3. On the Open Data Source dialog box, select STATGRAPHICS data file:

and then open the sample data file 93cars.sf6.

4. On the main toolbar under the STATGRAPHICS menu, press the button resembling a wizard's cap to invoke the StatWizard:

5. Be sure that the Select Analysis Based on Type of Data button is selected and then press OK.
    
6. On the next dialog box, use the list of column names and the arrow buttons to put 2 column names into the appropriate fields as shown below:

Be sure that the radio button for Type is set to General Numeric, indicating that the Y variable MPG Highway contains numeric values measured over a continuous scale. Then press OK.

7. On the Row Selection dialog box, be sure that the All Rows radio button is selected:

This indicates that all rows in the DataBook should be analyzed. Press OK.

8. When asked if you wish to transform any of the variables, press Yes:

9. The first transformation dialog box offers to transform MPG Highway:

On this dialog box, leave the Transformation checkmark on None and press OK.

10. The second transformation dialog box offers to transform Weight:

Set the Transformation radio button to Square Root.

11. The final StatWizard dialog box displays checkboxes for all statistical procedures that are designed to analyze the type of data you have specified:

Check the boxes next to Create a Scatterplot of Y versus X and Fit Y as a Function of X. Then press OK.

12. STATGRAPHICS will now indicate the number of analysis windows that it is about to create and ask you to confirm that it should proceed:

Press Yes.

13. Two new windows will now be created containing the procedures you have selected. One of the windows is a Simple Regression analysis, where a line has been fit relating MPG Highway to SQRT(Weight):

You may now use each of the analyses as if they had been selected from the main STATGRAPHICS menu.
 

Searching for Specific Statistics and Tests

1. To determine which STATGRAPHICS procedures calculate a particular statistical procedure or test, such as a probability plot, press the button resembling a wizard's cap to invoke the StatWizard and select the Search radio button:

2. Use the dropdown list to select Probability plot:

3. Select the Select Analysis by Name radio button to see a list of all statistical procedures that create probability plots:

4. Highlight Probability Plots and press OK to display the data input dialog box for that procedure:

5. Enter Engine Size into the data field and press OK to proceed as if you had selected that procedure from the main menu:

Repeating Analyses for Each Level of a BY Variable

1. On occasions, you may want to repeat one or more analyses for every unique value found in a selected column. For example, press the button resembling a wizard's cap to invoke the StatWizard and choose Select Analysis Based on Type of Data:

2. On the Data Selection dialog box, select Mid Price as the Y variable and press OK:

3. On the Row Selection dialog box, set the radio button to Each Unique value of and use the dropdown list to select Type:

4. When asked whether you wish to transform any of the variables, press No:

5. On the next dialog box, select Create a Frequency Histogram:

6. When the program asks whether you wish to proceed with the creation of 6 windows, press Yes:

7. STATGRAPHICS will now create a frequency histogram of Mid Price for each unique value of Type. To arrange the panes as shown below, select Window - Cascade from the main STATGRAPHICS menu:

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