Example 20. Two-Way ANOVA: Battery Data

An engineer is designing a battery for use in a device that would be subjected to extreme variations in temperature. Three choices of the plate material are possible, and the engineer tests these at three temperature levels. Four batteries are tested at each plate material/temperature combinations, all 36 tests being run in random order. The data on the lifetimes of the batteries (in hours) is shown below.

Source: Montgomery, D.C. (2001). The Design and Analysis of Experiments. John Wiley & Sons: New York.

Table 20: Battery Data

 Temperature (deg. F)
Plate Material1570125
M1130
155
74
180		34
40
80
75		20
70
82
58
M2150
188
159
126		136
122
106
115		25
70
58
45
M3138
110
168
160		174
120
150
139		96
104
82
60

Questions:

  1. Discuss the effect of material type and temperature on the battery lifetimes.
  2. Is there a choice of material type that would give uniformly long lifetime irrespective of the temperature level?

Keywords: Two-way ANOVA, main effects, interaction effects

Numerical Examples for use with
A First Course in Linear Model Theory by Ravishanker and Dey
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