For example, assume a psychologist gave a personality test measuring shyness to all 2500 students attending a small college. Using the numerical approach one might compute statistics such as the mean and standard deviation . These statistics convey information about the average degree of shyness and the degree to which people differ in shyness. Using the graphical approach one might create a stem and leaf display and a box plot . These plots contain detailed information about the distribution of shyness scores.
Graphical methods are better suited than numerical methods for identifying patterns in the data.
Numerical approaches are more precise and objective. Since the numerical and graphical approaches compliment each other, it is wise to use both. Inferential Statistics are used to draw inferences about a population from a sample . Consider an experiment in which 10 subjects who performed a task after 24 hours of sleep deprivation scored 12 points lower than 10 subjects who performed after a normal night's sleep. These are the types of questions answered by inferential statistics.