ABSTRACT
The subject of statistics arises in everyday conversation, in newspapers and on television. Whenever statistics are mentioned they are usually accompanied by the word ‘data’. Strictly speaking ‘data’ is a plural word, the singular being ‘datum’, but it is common practice to use it as if it is singular. Of course, to say anything with certainty we should need the data from the entire population. However, the theory of statistics enables us to say something with a specified probability by analysing samples selected at random from the population. There are fundamental differences between the theory of population statistics and the theory of sample statistics, and to reinforce this difference shall consider an example. Numerical data falls broadly into two categories: discrete data and continuous data. Faced with a collection of data, the statistician usually wishes to display the information in a clear easily understood and unbiased way.
