Homework Assignment 7
Due in Week 8 and worth 30 points
The experiment data in below table was to evaluate the effects of three variables on invoice errors for a
company. Invoice errors had been a major contributor to lengthening the time that customers took to pay
their invoices and increasing the accounts receivables for a major chemical company. It was conjectured
that the errors might be due to the size of the customer (larger customers have more complex orders), the
customer location (foreign orders are more complicated), and the type of product. A subset of the data is
summarized in the following Table.
Table: Invoice Experiment Error
Customer Size Customer Location Product Type Number of Errors
15
18
19
23
16
21
Customer Size: Small (-), Large
Customer Location: Foreign (-), Domestic
Product Type: Commodity (-), Specialty
Reference: Moen, Nolan, and Provost (R. D. Moen, T. W. Nolan and L. P. Provost. improving Quality
through Planned Experimentation. New York: McGraw-Hill, 1991)
Use the date in table above and answer the following questions in the space provided below:
1. What is the nature of the effects of the factors studied in this experiment?
2. What strategy would you use to reduce invoice errors, given the results of this experiment?