Frequency table

Bar charts for discrete data show the frequencies of the different values — i.e. the number of times each value occurs in the data set. A frequency table shows these frequencies in tabular form and is a useful summary of the distribution on its own right.

Calculating the mean

The mean of a discrete data set can be easily calculated from a frequency table.

Mean household size

Note that the mean number of individuals per household is not a whole number. This is perfectly reasonable for the mean of a discrete variable.

Using a spreadsheet (Optional)

Calculating a mean from a frequency table can be easily done on a spreadsheet.

Calculating the standard deviation

The standard deviation of a discrete data set can be evaluated on a spreadsheet in a similar way, based on the formula

Note that the summation on the left would be over all 600 households, whereas the summation on the right is only over the 7 distinct household sizes.