An introduction to everyday statistics--2.

Objectives x Describe central tendency and variability x Summarising datasets containing two variables In covering these objectives we will deal with the following terms: x Mean, median and mode x Percentiles x Interquartile range x Standard deviation x Standard error of the mean In the first article of this series, we discussed graphical and tabular summaries of single datasets. This is a useful end point in its own right but often in clinical practice we also wish to compare datasets. Carrying this out by simply visually identifying the diVerences between two graphs or data columns lacks precision. Often therefore the central tendency and variability is also calculated so that more accurate comparisons can be made.