The data composition presents you with a concern about the sampling and analysis. Since the number of items coming from each crew is different in the before and after data, the analysis could possibly indicate that the after data $(60\%$ is from Crew C$)$ is better than the before data $(60\%$ is from Crew A$)$ regardless of any quality improvements. You feel obligated to discuss your concerns with the plant manager. From your previous discussions with the plant manager, you have the impression that the plant manager needs to present the analysis to upper management and will want you to perform the analysis with the present data. So$,$ you want to have in your mind the reasons why the analysis should not proceed with all data as it is in the current form. From your past experience, you believe that your concern will become accepted by the plant manager if you can propose a solution to the potential problem.