MA Soc: Lab Materials Week 7

Week 7 Lab

Spreadsheets and the standard deviation

Spreadsheets are occasionally very useful for manipulating data and presenting numbers. They have a completely different way of working from Stata, however. You can enter text, numbers and formulas in the cells. The formulas can be simple (e.g. =5+6, which will display 11 in the cell) or arbitrarily complex (e.g. =A1+A2, which adds the values of two other cells; =normsdist((A1-B1)/B2) which returns the area of the normal distribution to the right of the value in cell A1, for a distribution with a mean of the value in cell B1, and a standard deviation in cell B2).

Exercise 1: Calculating a Standard deviation

If we have the following data about 10 people (minutes spent in domestic work per day), how do we calculate the standard deviation:

 1: 44
 2: 36
 3: 41
 4: 36
 5: 46
 6: 49
 7: 43
 8: 44
 9: 41
10: 54
These are the Xs, i.e. X1 to X10 The steps are as follows:

  1. Enter the data in a spreadsheet in a single column
  2. Calculate the total at the bottom of the column (=sum(...))
  3. Calculate the mean (total divided by 10) -- this is X-bar
  4. In the next column calculate the deviation (Xi minus X-bar)
  5. In the next column calculate the squared deviations, (Xi minus X-bar)2
  6. Sum the squared deviations
  7. From these calculate the standard deviation, using the formula sheet

Brendan Halpin
Department of Sociology, University of Limerick
F1-002, x 3147;