Pipeline operators estimate that it costs between $75 and
$500 in U.S. currency to replace each seal, thus making
the Clarkson longer-lasting valves more attractive. Tyco does business with pipeline companies around the world.

Suppose in an attempt to develop marketing materials,
Tyco marketers are interested in determining whether
there is a signi?cant difference in the cost ofreplacing
pipeline seals in different countries.Four countries—
Canada,Colombia,Taiwan,and the United States—are
chosen for the study.Pipeline operators from equivalent
operations are selected from companies in each country.
The operators keep a cost log ofseal replacements.A ran-
dom sample ofthe data follows.Use these data to help
Tyco determine whether there is a difference in the cost of
seal replacements in the various countries.Explain your
answer and tell how Tyco might use the information in
their marketing materials.

Suppose that Tyco now uses a similar system
and wants to test to determine whether lead-times differ
signi?cantly according to the type ofvalve it is manufac-
turing.As a control ofthe experiment,they are including
in the study,as a blocking variable,the day ofthe week the
valve was ordered.One lead-time was selected per valve
per day ofthe week.The data are given here in weeks.
Analyze the data and discuss your ?ndings


Canada Colombia Taiwan United States
$215 $355 $170 $230
205 280 190 190
245 300 235 225
270 330 195 220
290 360 205 215
260 340 180 245
225 300 190 230

Type of Valve
Safety Butter?y Clack Slide Poppet Needle
Monday 1.6 2.2 1.3 1.8 2.5 0.8
Tuesday 1.8 2.0 1.4 1.5 2.4 1.0
Wednesday 1.0 1.8 1.0 1.6 2.0 0.8
Thursday 1.8 2.2 1.4 1.6 1.8 0.6
Friday 2.0 2.4 1.5 1.8 2.2 1.2

Black, Ken (2011-12-01). Business Statistics: For Contemporary Decision Making,