Convert to Standard Scores
This page will convert the individual values in a data set into their corresponding standard scores according to the conventional formula
 zi = | Xi−M SD |
| where
Xi = any particular value in the data set; M = the mean of the data set; and SD = the standard deviation of the data set. |
The option is provided for converting values of X to values of z using either the descriptive standard deviation or the inferential standard deviation:
| Descriptive SDQ |
| Inferential SDSD =  (Xi−M)2N SD = (Xi−M)2N−1 | ||||||
The descriptive SD is the standard deviation of this particular sample of X values; the inferential SD is the estimated standard deviation of the population from which the sample is drawn.
Procedure:
- Entering Data Directly into the Text Field:T
After clicking the cursor into the text area labeled Data Entry, enter the values for your data set in sequence, pressing the carriage return key after each entry except the last. (On a Macintosh platform, the carriage return key is labeled 'Return'; on a Windows platform it is labeled 'Enter.')
- Importing Data via Copy & Paste:T
Within the spreadsheet application or other source of your raw data, select and copy the column of data for the set. Then return to your web browser, click the cursor into the text area for Data Entry and perform the 'Paste' operation from the 'Edit' menu.T
- Data Check:T
Make sure that the final entry in the list is not followed by a carriage return. (A carriage return after the final entry will be interpreted as an extra data entry whose value is zero. Importing data via the copy and paste procedure will almost always produce an extra carriage return at the end of a column.) After all values for the raw data set have been entered, click the cursor immediately to the right of the final entry in the list, then press the down-arrow key. If an extra line is present, the cursor will move downward. Extra lines can be removed by pressing the down-arrow key until the cursor no longer moves, and then pressing the 'Backspace' key (on a Mac platform, 'delete') until the cursor stands immediately to the right of the final entry.T
- When all all values have been entered, select and click one of the
«Convert to z» buttons.T
- Exporting Results:T
When copied and pasted into a spreadsheet application, the values listed in the 'Converted Data' field will align as adjacent columns. T
| Data Entry | Converted Data |
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©Richard Lowry 2001-
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