Box-Cox Transformation

This example uses the example data set Aircraft.sta, which is distributed with STATISTICA. From the File menu, select Open Examples. Double-click the Datasets folder, and locate and open Aircraft.sta.

The goal of this example is to perform a Box-Cox transformation of one dependent variable, VISC, and save the transformed values back to the original data set.

1.) With the data set open, add a new variable. This will be where STATISTICA writes the transformed valued for use in analyses. For this example, add the variable after VISC, and name it Visc BoxCox. There are several ways to add a new variable.

a) Data – Variables – Add

Box-Cox Transformation

b) Or from the Vars menu, select Add

Box-Cox Transformation

c) Or double-click in the gray space around the data in a spreadsheet.
Box-Cox Transformation

2. The spreadsheet should now look like this:

Box-Cox Transformation
3. From the Data menu, select Box-Cox Transformation.

Box-Cox Transformation
4. In the Box-Cox Transformation dialog, click the Variables button, and the select the variable you want to transform. For this example choose VISC. Click OK in the variable selection dialog.

Box-Cox Transformation

5. The values used for computations can be adjusted if desired. But for this example, we will leave them as is.

6. Click OK in the Box-Cox Transformation dialog to display the Box-Cox Results dialog.

Box-Cox Transformation

7. There are several options to display results such as plots and summaries of the estimated values. But, to place the transformed values back to the original data set, click the Write back to input spreadsheet button.

Box-Cox Transformation

8. The Assign statistics to variables for saving in input data dialog is displayed. Here, we will specify to which variable to write the transformed values back to.

9. Under Statistics, choose the variable that was transformed, VISC. Under Variables, choose the new variable location for the transformed data, Visc BoxCox. Then click Assign.
Box-Cox Transformation

10.  The assignment will be displayed in the bottom box.

Box-Cox Transformation

11. Click OK. You may see a warning message about an analysis being in progress. That is fine, just click OK. The original spreadsheet will be updated to include the transformed values in the Visc BoxCox variable.

Box-Cox Transformation

About statsoftsa

StatSoft, Inc. was founded in 1984 and is now one of the largest global providers of analytic software worldwide. StatSoft is also the largest manufacturer of enterprise-wide quality control and improvement software systems in the world, and the only company capable of supporting its QC products worldwide, with wholly owned subsidiaries in all major markets (StatSoft has 23 full-service offices, on all continents), and its software is available in more than 10 languages.

Posted on February 27, 2013, in Uncategorized. Bookmark the permalink. Leave a comment.

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