An artičle in the ACT Materials Journal (Vol. 84, 1987, pp. 213-216) describes several experiments investigating the rodding of concrete to remove trapped air. A 3-inch x 6-inch cylinder was used, and the number of times this rod was used is the design variable. The resulting compressive strength of the concrete specimen is the response. The data are shown in the following table. Compressive Strength (psi) Rodding Level Observations 10 1530 1530 1440 15 1610 1650 1500 20 1560 1730 1530 25 1500 1490 1510 (a) Is there any difference in compressive strength due to the rodding level? Use a = 0.05. Calculate to 2 decimal places fo: Is there statistical evidence to say that rodding level affects compressive strength? (b) Find to 2 decimal places the P-value for the F-statistic computed in part (a). P-value - i (c) Analyze the following residual plots to determine model adequacy. Does the assumption of normality seem reasonable? Does there appear to be an outlier in the data? Does the assumption of constant variance seem reasonable?

Linear Algebra: A Modern Introduction
4th Edition
ISBN:9781285463247
Author:David Poole
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Chapter7: Distance And Approximation
Section7.3: Least Squares Approximation
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Nomal Probability Plot of the Residuals
(response is STRENGTH)
2.
-1
-2
-100
100
Residual
ResidualsVersusRODDING
(po nse Is STRE NGTH)
100 -
-100
10
16
20
25
RODDING
ResdualsVersusthe Fitted Values
(sponses STRE NGTM)
100
-100
1600
1560
1600
F ted Value
Nomal Score
erpsay
npsay
Transcribed Image Text:Nomal Probability Plot of the Residuals (response is STRENGTH) 2. -1 -2 -100 100 Residual ResidualsVersusRODDING (po nse Is STRE NGTH) 100 - -100 10 16 20 25 RODDING ResdualsVersusthe Fitted Values (sponses STRE NGTM) 100 -100 1600 1560 1600 F ted Value Nomal Score erpsay npsay
An article in the ACI Materials Journal (Vol. 84, 1987, pp. 213-216) describes several experiments investigating the rodding of concrete
to remove trapped air. A 3-inch x 6-inch cylinder was used, and the number of times this rod was used is the design variable. The
resulting compressive strength of the concrete specimen is the response. The data are shown in the following table.
Compressive Strength (psi)
Rodding Level
Observations
10
1530
1530
1440
15
1610
1650
1500
20
1560
1730
1530
25
1500
1490
1510
(a) Is there any difference in compressive strength due to the rodding level? Use a = 0.05.
Calculate to 2 decimal places fo:
Is there statistical evidence to say that rodding level affects compressive strength?
(b) Find to 2 decimal places the P-value for the F-statistic computed in part (a).
P-value -
(c) Analyze the following residual plots to determine model adequacy.
Does the assumption of normality seem reasonable?
Does there appear to be an outlier in the data?
Does the assumption of constant variance seem reasonable?
Transcribed Image Text:An article in the ACI Materials Journal (Vol. 84, 1987, pp. 213-216) describes several experiments investigating the rodding of concrete to remove trapped air. A 3-inch x 6-inch cylinder was used, and the number of times this rod was used is the design variable. The resulting compressive strength of the concrete specimen is the response. The data are shown in the following table. Compressive Strength (psi) Rodding Level Observations 10 1530 1530 1440 15 1610 1650 1500 20 1560 1730 1530 25 1500 1490 1510 (a) Is there any difference in compressive strength due to the rodding level? Use a = 0.05. Calculate to 2 decimal places fo: Is there statistical evidence to say that rodding level affects compressive strength? (b) Find to 2 decimal places the P-value for the F-statistic computed in part (a). P-value - (c) Analyze the following residual plots to determine model adequacy. Does the assumption of normality seem reasonable? Does there appear to be an outlier in the data? Does the assumption of constant variance seem reasonable?
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