Calculating the standard deviation using Excel
Excel has functions to calculate the population and sample standard deviations. The appropriate commands are entered into the formula bar towards the top of the spreadsheet and the corresponding cells in the spreadsheet are updated to show the result.
For an example of calculating the population standard deviation, imagine you wish to know how fuel-efficient a new car that you have just purchased is. You calculate how many kilometres you have done per litre on your first five trips. This information is presented as column A of the spreadsheet (figure 5). As you have only made 5 trips you do not have any further information and you are therefore measuring the whole population at this point in time. The command to find the population standard deviation in Excel is =STDEVP(VALUES) and in this case the command is =STDEVP(A2:A6) which gives an answer of 0.49.