The values of the two variables are plotted on a graph paper. We get two curves one for x variables and another for y variables. These two curves reveal the direction and closeness of the two curves and also reveal whether or not the variables are related. If both the curves move in the same direction i, e, parallel to each other either upward or downward correlation is said to be positive. On the other hand if they move in opposite directions then the correlation is said to be negative .
The above methods is used in the case of time series. This methods also does not reveal the extent to which the variables are related.