evaluate the effects of three variables on invoice errors, statistics homework help

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
–	+	–	6
+	+	–	2
–	–	+	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?