# HP 50g Calculator - Calculating Single Variable Standard Deviation using the Pre-programmed Features

Introduction
Standard deviation is a statistic that measures the variability or dispersion of a set of data. It is calculated from the deviations (distances) between each data value and the sample mean, and is often represented by the letter ‘s’. The more disperse the data is, the larger the standard deviation. The standard deviation squared is called the variance.
Calculating single-variable statistics
One method for calculating single variable, standard deviation involves launching one of the pre-programmed statistical applications by pressing . Highlight the desired option and press to select it. Press to enter data into the columns of the ∑DAT matrix. The procedure is as follows:
1. Press .
2. Select ‘Single-Var..’ by pressing (the F6 key). An input form labeled ‘SINGLE-VARIABLE STATISTICS’ is displayed.
3. Press the soft menu key (the 'F1' key).
4. Enter the data in column 1. On the last entry, press twice to reopen the SINGLE VARIABLE INPUT form.
5. Press to highlight the ‘Type’ field and press the soft menu key. The options for sample or population statistics are displayed in the choose menu.
1. ‘Sample’ is a set of numbers, usually taken from a much larger population.
2. ‘Population’ is a set of all numbers, which is the whole population.
6. Select ‘Sample’ or ‘Population’, then press the 7. Press to the ‘Std Dev’ field, then press the 8. Press the soft menu key. The result is displayed on the stack.
Example for calculating single-variable statistics
Below is an example for entering a set of data and finding the single-variable statistics results. The example is calculated in RPN mode, however, it may be calculated in either RPN or Algebraic mode.
1. Press .
2. Select ‘Single-Var..’. An input form labeled ‘SINGLE-VARIABLE STATISTICS’ is displayed.
3. Press the 4. Enter the data below in column 1. In this example, the row numbers appear before each entry to verify the entries. Use the arrow keys to highlight the next field in Column 1 prior to entry, if necessary :
Figure : Entering the data Using this method for data entry, the data in Column 1 displays as shown in the above figure.
1. 2.1, press .
2. 1.2, press .
3. 3.1, press .
4. 4.5, press .
5. 2.3, press .
6. 1.1, press .
7. 2.3, press .
8. 1.5, press .
9. 1.6, press .
10. 2.2, press .
11. 1.2, press .
12. 2.5, press twice.
5. Press to the ‘Type’ field and press the soft menu key. The option of sample or population statistics will be displayed in the choose menu.
6. Select ‘Sample’ and then press the 7. Use the arrow keys to highlight the various fields and the soft menu key to select:
• Mean
• Std Dev
• Variance
• Total
• Maximum
• Minimum
8. Press the soft menu key. Press the up arrow key to view the results displayed below:
Figure : Results for Sample statistics Similarly, to calculate the results for Population statistics for the same data, at this point, press . Select ‘Single-Var..’ and press . Highlight the ‘Type’ field using the cursor keys and press . Highlight ‘Population' and press . Repeat steps 7 and 8 above. The results are shown below.
Figure : Results for Population statistics 