DATA MINING
Desktop Survival Guide by Graham Williams 


We now start to explore how the data in each of the variables is distributed. This might be as simple as looking at the spread of the numeric values, or the number of entities having a specific value for a variable. Another aspect involves measuring the central tendency of data, or determining the mean and median. Yet another is a measure of the spread or variance of the data from this central tendency. We again begin with textual presentations of the distributions, and then graphical presentations.