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Now that the team has determined a way to adjust the process to change viscosity by adjusting the steam pressure, Maria has been asked to determine a strategy for monitoring and controlling viscosity during production. She has seen that there is not much consistency in what is currently being done and that each line operator has their own practice for how often they monitor viscosity and how they adjust process settings based on what they see.

Maria use a response surface design to determine factor level combinations that will deliver the desired viscosity.

Maria discusses her first year on the job learnings with her professor and receives a valuable resource list.

Maria and Alex meet the next morning to plan the screening design to identify the important factors affecting viscosity. Maria had already decided on a 16-run resolution 4 design for her six factors. She and Alex will now need to decide on the ranges for each factor.

Maria uses regression and correlation analyses to determine ingredient and production factors affecting viscosity.

The issue of dispensation of product was put on hold due to potential out of specification viscosity levels passed, and the team focus has resumed delivering the best product on a consistent basis. Lisa's recent feedback had been that there was a positive impact on the BBQ lines since the SPC system was implemented. She asks Maria to present the dynamic SPC monitoring system implemented earlier on the BBQ lines to the operations management team.

Steve opens up the research and development leadership team meeting bragging about the power of the work that Maria has just finished. Design of experiments has presented a powerful approach that had not been used before. Maria's work has helped the plant not only to deliver more consistent BBQ viscosity, but also the systematic approach has led to a better understanding of how factors such as steam pressure and line speed affect viscosity. Steve has in mind several improvement opportunities, and he hopes that by applying the design of experiments methodology to them, the results will be similarly positive.

Lisa is right! As a plant manager, she ought to be able to demonstrate that the investment made in a new line is a good investment. Alternatively, if the new asset brings no additional, or only marginal, benefit why should she upgrade the rest of the lines? Lisa needs more than a summary of line performances. She should be able to defend the case with confidence, that the asset investment has merits. She ought to be able to clearly answer the question: Is there a significant difference between line 4 and line 6 viscosities?

Maria uses analysis of variance (ANOVA) and multiple paired comparison (MPC) procedures to compare the production line viscosities.

Maria learns about statistical approaches to sampling and develops a sampling plan to determine product dispensation.

Maria is asked to compare the viscosities from two production lines and uses descriptive statistics and graphs to make a determination.

Maria discovered large differences in performance of all production lines across the two production shifts, with generally consistent production within a shift. First shift production is consistently higher in viscosity. But, as Lisa pointed out, it is not clear whether the differences in viscosities between the shifts are real differences or they are due to the measurements being taken by different lab technicians.