Correlation defined as linear relationship between two variables. Correlation coefficient (r) is used to measure linear association between two variables and its range varies between -1 to +1. There are two types of correlation namely positive and negative. r=+1 represents perfect positive correlation whereas r=-1 represents perfect negative correlation. Positive correlation tells both indicators are moving in same direction for e.g. If prices of crude oil and Natural gas are positively correlated and there is an increase in price of crude oil then price of Natural gas will also increase. On the other hand negative correlation between the same indicators, if there is increase in price of one will decrease the price of others.