Variation

The concept of variation in statistics is basic. Measure of central tendency and measure of dispersion both describes some quantitative data. In statistics, however, these measures only "describe" the characteristics of data but not demonstrate the cause and effect of it. Take variation for example, why is there such dispersion?

In my opinion, central tendency reflects the habits of human or inertia of nature, and variation reflects other causes of different performances of human or phenomenon of nature from the habits or inertia. Change of central tendency means chage of habits or inertia. Some variation leads to such changes due to its strengthened cause and effect operation.