Step 1

Scatterplot matrix:

A scatterplot matrix is an array or a collection of scatterplots, consisting of all possible scatterplots of the response variable drawn against each predictor and also, between every pair of predictors.

Step 2

A careful inspection of the scatterplot matrix reveals the nature of relationship between all the variables in the data set. It is known that it is reasonable to fit a regression plane to a data, only if there exists a linear relationship or at least, a somewhat linear relationship of the response variable with each of the predictor variables.

Thus, the plot that is useful for deciding whether it is reasonable to find a regression plane for a set of data points involving several predictor variables is a scatterplot matrix.

Scatterplot matrix:

A scatterplot matrix is an array or a collection of scatterplots, consisting of all possible scatterplots of the response variable drawn against each predictor and also, between every pair of predictors.

Step 2

A careful inspection of the scatterplot matrix reveals the nature of relationship between all the variables in the data set. It is known that it is reasonable to fit a regression plane to a data, only if there exists a linear relationship or at least, a somewhat linear relationship of the response variable with each of the predictor variables.

Thus, the plot that is useful for deciding whether it is reasonable to find a regression plane for a set of data points involving several predictor variables is a scatterplot matrix.