Data Types

To select a statistical method, one will need to identify what types of data he/she plans to collect. The choice of descriptive and analytical methods depends crucially on the type of data involved. Three data types are continuous measured/scale, ordinal and categorical/nominal. The first two types are concerned with the measurement of some characteristic. The final type is just a classification with no sense of measurement. Clinical observations often produce continuous measured data, such as weights, volumes, timings, concentrations, and pressures. Continuous measured data needs to be subdivided according to whether it follows a normal distribution or not, as many statistical methods will only work with normally distributed data. Non-normal data needs alternative approaches. It is best to avoid statistical tests for normality as the results are easily misinterpreted. The ordinal data consists of categorizations, but the important thing is that the categories have a natural order to them.