Final answer:
b. Residual Plot
A scatter diagram with the residuals on the vertical axis and the explanatory variable on the horizontal axis is known as a Residual Plot.
Step-by-step explanation:
A scatter diagram with the residuals on the vertical axis and the explanatory variable on the horizontal axis is called a Residual Plot. In statistical analysis, a residual plot is an important diagnostic tool that is used after fitting a regression model. It helps in checking the randomness of the residuals which implies that the model is adequately capturing the information in the data. A residual plot shows the residuals on the vertical axis and the independent variable (or the predicted values) on the horizontal axis. If the points in a residual plot are randomly dispersed around the horizontal axis, a linear regression model is appropriate for the data; otherwise, a non-linear model may be more suitable.