STATISTICA Blogs

STATISTICA analysis tools are designed to accept data that follow an explicit structure. Specifically, each row or case should represent one individual experimental unit. If the data measure the blood pressure of patients, then each patient will have one row. The variables will provide the information about that individual patient.

This example uses an experimental data file from Excel's Help files. The data show growth measurements of plants from two levels of groups and two levels of trials. The data have a total of 16 observations. The following image shows how the data are arranged in Excel.

To perform an analysis on this data in STATISTICA, it must first be rearranged to meet STATISTICA data structure standards.

To import this Excel file into STATISTICA, select Open from the File menu. In the Open dialog, browse to the Excel file, select it, and click the Open button. In the Opening file dialog, click the Import selected sheet to a Spreadsheet button. Click OK in the Select Sheet to Import dialog. Click OK in the Open Excel File dialog. The Excel file is displayed in a STATISTICA Spreadsheet.

After importing the data into STATISTICA, some edits are necessary. First, each row must indicate the trial from which it came. Use the fill/copy down option to achieve this, i.e., place the mouse pointer on the black “handle” at the lower-right corner of the trial 1 cell and, pressing the mouse button, drag down through the next 3 cells. Release the mouse button, and trial 1 will be displayed in the 4 cells. Repeat for the cells under trial 2.

The spreadsheet below shows the data after filling in trial information for all rows.
 

Next, the data must be rearranged. From the Data menu, select Unstacking/Stacking to display the Unstacking/Stacking dialog. Select the Stacking tab.

Click the Variables button and in the variable selection dialog, select variables group 1 and group 2, and click the OK button. In the Destination variable name field, enter the name Measurement, and in the Code variable name field, enter the name Group.

Click OK and a new spreadsheet is created, which holds the data in the format expected by STATISTICA, with each experimental unit in its own row and each factor in its own column. The data are now ready for analysis in STATISTICA.

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