Question

Why is it advisable to generate a scatterplot before computing a correlation coefficient between two variables? Describe how a scatterplot might differ when viewing correlations that represent positive, negative, and no relationship between predictor and criterion variables. Is it possible to have a relation between variables that systematic (i.e., reliable and predictable) yet not linear?

Answer 1

Scatter plot plays a great role in viewing the data in many ways----

1)what is trend of the data, increasing, decreasing or constant.

2) Is any outlier present in the data or not.

why scatter plot is necessary before finding correlation coefficient----

1) it will give pre idea about the relationship between these two variable.

2) it will give idea about the linear relationship between two variable, sometime relation between x and y is non linear but correlation coefficient is not zero(as correlation coefficient is a measure of linear relation between two variable), gives a wrong interpretation of data....By scatter plot we can get an idea about type of relationship linear or nonlinear.