STAT 425 Final Project Fall 2021
Final Project
Instructor: A. Chronopoulou
Bubble Wrap Experiment Description
Company XX is a manufacturer of several types of protective packaging, including bubble wrap
sold in both retail and bulk. The objective of this project is to determine the best operating
conditions for the bubble wrap lines to increase production capacity.
Variables such as extrusion rate, temperature, line speed, and percent loading of additives
were key factors that were considered in the study. After preliminary experiments, the engineers
decided that line speed, and percent loading of additives were the most significant fac-
tors and thus a complete randomized (also called factorial) design was implemented with these
two factors:
Factor Levels
Line Speed (m/mm) 36 37 38
Loading of Additives (%) 0 2 4
The response variable was the production rate measured in lbs/hr. The experiment was
replicated 3 times and the randomization order for each replication was also recorded.
Our goal is to find the optimal combination of line speed and percent load of additives
that results in the highest production rate.
The data can be found in the bubblewrap.csv data set on Moodle.
Deadline
One report per group should be submitted by Monday, December 13 @ 11.59pm.
Instructions
The final project can be completed either individually or in groups of 2-3 students. If you decide
to work in a group, you must complete both parts of the problem.
1
STAT 425 Final Project Fall 2021
Part I
In this project, you should use models and methods we discussed in class to analyze the
data from this experiment. Your goal is to answer the question in the model description (i.e.
find the optimal combination of line speed and percent load of additives that results
in the highest production rate) , so make sure that you use appropriate hypothesis tests to
reach a conclusion. Finally, you should make sure to check the model assumptions by performing
appropriate diagnostic tests and taking remedial measures, if needed.
Part II – to be completed by groups
During the experiment, the team observed that the quality of the bubble wrap was not accept-
able for Replication 2, runs 2,3, and 5, which resulted in discarding the produced bubble wrap.
Re-do the analysis in Part I with the appropriate modifications.
Deliverables
The case study should be submitted on Gradescope as a group (only once case study per group)
or individually (if you worked on your own). You should submit:
(1) a PDF file containing a 2-3 executive summary of the analysis. You need to make sure
that your report is professionally and clearly written, addressed to someone who knows
statistics. You should also include a concluding paragraph where you should state your
conclusions in layman’s terms. Any necessary plots or R output should be attached in an
appendix. You should include no R code in the summary.
(2) an R Markdown and corresponding HTML file with comments with all the R code that
you built to analyze the data set.
A rubric on which the grading of the case study will be based is posted on Moodle for your
reference.
2