M.8—Distributions, descriptive statistics and error bars

Mean, median, mode, range, standard deviation, standard error and confidence intervals describe different aspects of a dataset.

Use the statistic that matches the distribution and explain what error bars represent before comparing them.

A skewed dataset may be better summarised by a median, while standard error describes uncertainty in a mean rather than spread of individual values.

Error bars are not interchangeable; SD, SE and confidence intervals answer different questions.