Quality Quiz:
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The division manager, Emily Dickinson, has decided that Hyde N. Sikh has not lived up to her expectations, so she releases him from his responsibilities. While quality manager Polly Yurathane had actually been responsible for miscalculations made by Hyde N. Sikh, she was unscathed, and moved eagerly to work with her new boss, Hy O. Pinyon, a statistician who, she believes, will help her to learn more about statistics.
Hy comes across a regression model prepared by Polly earlier in the year, and asks her to explain the results:
 = cost
 = amount of coal mined
 depth of shaft
Month |
Total cost |
Tons of coal |
Depth of shaft |
JAN |
5 |
10 |
5 |
FEB |
9 |
20 |
5 |
MAR |
13 |
30 |
5 |
APRIL |
14 |
10 |
20 |
MAY |
18 |
20 |
20 |
JUNE |
22 |
30 |
20 |
JULY |
20 |
10 |
30 |
AUG |
24 |
20 |
30 |
SEPT |
28 |
30 |
30 |
Regression for cost:
Variable |
Coefficient |
Standard error |
Beta coefficient
|
t-value |
p-value |
Constant |
2 |
1.067 |
0 |
|
<0.001 |
Tons mined |
0.4 |
1.581 |
1 |
3.162 |
0.007 |
Shaft size |
0.6 |
1.005 |
3 |
5.969 |
<0.001 |
|
|
|
|
|
|
R-squared |
0.7526 |
|
|
|
|
R-squared (adj) |
0.7196 |
|
|
|
|
As he examines the data, Hy refers to the regression coefficient of  and  . Polly, eager to convince him of her statistical prowess, explains their meaning, noting that the printout also includes beta coefficients, which represent standardized values.
Is Polly’s assessment of this meaning accurate?
a) Yes.
b) No.
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