Final answer:
The scatter plot method allows for visual inspection of data to assess the relationship between variables and decide if a linear model is appropriate before analysis.
Step-by-step explanation:
One advantage of the scatter plot method of separating a mixed cost into its fixed and variable components is that it allows a cost analyst to inspect the data visually. By using size as the independent variable and cost as the dependent variable, a scatter plot enables the analyst to draw the plot and look for a relationship between the variables. If the pattern of the points suggests a linear relationship, the analyst can proceed to calculate the least-squares line with the equation î = a + bx, as well as find the correlation coefficient to determine the strength and significance of the relationship. However, if the scatter plot indicates a non-linear relationship, as in the case where a curve fits the data points better than a line, a statistician may choose to use more sophisticated methods to model the costs. Overall, this visual inspection step is crucial to deciding whether a linear model is appropriate before performing further analysis.