Quote from MarketMafia:
There is a thing name " Correlation". I think it will answer your question.
cor·re·la·tion (kôr'ə-lā'shən, kŏr'-) pronunciation
n.
1. A causal, complementary, parallel, or reciprocal relationship, especially a structural, functional, or qualitative correspondence between two comparable entities: a correlation between drug abuse and crime.
2. Statistics. The simultaneous change in value of two numerically valued random variables: the positive correlation between cigarette smoking and the incidence of lung cancer; the negative correlation between age and normal vision.
3. An act of correlating or the condition of being correlated.