Data and statistics
The purpose of most studies is to collect data to obtain
information about a particular area of research. Our data
comprise observations on one or more variables; any quantity
that varies is termed a variable. For example, we may
collect basic clinical and demographic information on
patients with a particular illness. The variables of interest
may include the sex, age and height of the patients.
Our data are usually obtained from a sample of individuals
which represents the population of interest. Our aim is
to condense these data in a meaningful way and extract
useful information from them. Statistics encompasses the
methods of collecting, summarizing, analysing and drawing
conclusions from the data: we use statistical techniques to
achieve our aim.
Data may take many different forms. We need to know
what form every variable takes before we can make a decision
regarding the most appropriate statistical methods to
use. Each variable and the resulting data will be one of two
types: categorical or numerical