Correlation is a technique that help us to find or define a relationship between two variables.
A positive correlation means that an increase in one quantity leads to an increase in another quantity
A negative correlation means with increase in one quantity the other quantity decreases.
+1 tells about a a perfect positive linear relationship and −1 indicates a perfect negative linear relationship.
Values between 0 and 0.3 tells about a weak positive linear relationship, values between 0.3 and 0.7 shows a moderate positive correlation and a correlation of 0.7 and 1.0 states a strong positive linear relationship.
Values between 0 and -0.3 tells about a weak negative linear relationship, values between -0.3 and -0.7 shows a moderate negative correlation and a correlation value of of -0.7 and -1.0 states a strong negative linear relationship.
As the number of hours increases, the number of points earned on the test increases. Thus, the two variables are positively correlated.
Thus, the coefficient correlation between two variables can be given by r = 0.70, that shows a moderate positive correlation.
