ANCOVA Output for Field 2009

7/27/2019 ANCOVA Output for Field 2009

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Between mildew and FHB, Field 2009

Tests of Between-Subjects Effects

Dependent Variable:Perofinfectedspikesnormal

Source Type III Sum of

Squares df Mean Square F Sig.

Corrected Model 2552.277a 29 88.010 .945 .569

Intercept 527.150 1 527.150 5.660 .031

Varieties 586.819 14 41.916 .450 .928

mildewareatwevthjoun 50.846 1 50.846 .546 .471

Varieties *

mildewareatwevthjoun

541.918 14 38.708 .416 .946

Error 1397.020 15 93.135

Total 22763.502 45

Corrected Total 3949.297 44

a. R Squared = .646 (Adjusted R Squared = -.038)

The interaction is not significant, F (14, 15) = .416, p = .946

Levene's Test of Equality of Error Variancesa

Dependent Variable:VAR00008

F df1 df2 Sig.

1.600 14 30 .137

Tests the null hypothesis that the error variance

of the dependent variable is equal across groups.





Corrected Model 36.845a 15 2.456 2.877 .007

Intercept 16.237 1 16.237 19.017 .000

VAR00007 .463 1 .463 .542 .468

Varieties 36.500 14 2.607 3.053 .005

Error 24.761 29 .854

Total 920.130 45


a. R Squared = .598 (Adjusted R Squared = .390)


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The relationship between the covariate (mildew) and the dependent (FHB) variable, is not

significant, F (1, 29) = .542, p .468. This shows that there is no relationship (effect) between

the covariate and the dependent variable.

W2=SSB -(K-1)MSW/ SST+MSW

SSB = SS (for independent variable), MSW (MS for error), SST (SS for total).

W2= 36.500-14(.854)/61.506+.854

=-0.39=(39%).

This means that the seven barley varieties (the independent variable) account for

approximate 39% of the total variance in the % of infected grains with FHB scores (the

dependent variable), controlling for the effect of their mildew scores (the covariate). The

main effect for the independent variable (varieties) is not significant controlling for the effect

of the covariate (mildew).

F (1, 29) = .542, p .468 w2

= .39. This shows that there is no relationship (effect) between thecovariate and the dependent variable.

Conclusion.

A preliminary analysis evaluating the homogeneity-of-regression (slopes)assumption indicated that the relationship between the covariate and thedependent variable did not differ significantly as a function of the independentvariable, F (14, 15) = .416, p = .946. The ANCOVA was not significant, F(6, F(1, 29) = .542, p .468 w2= .39. However, 39% (w2 = 0.39) of the total variancein FHB achievement scores was accounted for by the seven barley varieties

controlling for the effect of the mildew scores.

Estimated Marginal Means


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Varieties


Varieties

Mean Std. Error

95% Confidence Interval

Lower Bound Upper Bound

dimension1

Dore 5.380a .551 4.253 6.508

2.00 3.968a .561 2.821 5.115

3.00 4.950a .595 3.733 6.166

4.00 4.435a .615 3.177 5.692

5.00 4.753a .571 3.586 5.920

6.00 3.875a .534 2.784 4.966

7.00 3.724a .535 2.631 4.818

8.00 4.619a .561 3.471 5.767

9.00 3.935a .552 2.805 5.065

10.00 5.219a .538 4.119 6.319

11.00 4.584a .544 3.471 5.696

12.00 5.248a .550 4.123 6.372

13.00 1.587a .547 .468 2.706

14.00 3.733a .576 2.555 4.910

15.00 5.509a .957 3.552 7.466

a. Covariates appearing in the model are evaluated at the following

values: VAR00007 = 5.3041.

Profile Plots

Between mildew and yield


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Dependent Variable:Seedperplantnormal



Corrected Model 36.550a 29 1.260 6.134 .000

Intercept 23.556 1 23.556 114.642 .000

Varieties 8.598 14 .614 2.989 .022

mildewareatwevthjoun .079 1 .079 .386 .544

Varieties *

mildewareatwevthjoun

5.242 14 .374 1.822 .130

Error 3.082 15 .205

Total 390.252 45



The interaction is not significant, F (14,15) = .1.822, p = .130.

Levene's Test of Equality of Error Variancesa

(LOG)Dependent Variable:VAR00002

F df1 df2 Sig.

2.115 14 28 .045

Tests the null hypothesis that the error variance

of the dependent variable is equal across groups.

a. Design: Intercept + VAR00008 + Varieties





Corrected Model 1.128a 15 .075 12.679 .000

Intercept .143 1 .143 24.107 .000

VAR00008 .001 1 .001 .107 .746

Varieties 1.103 14 .079 13.286 .000

Error .160 27 .006

Total 8.705 43



The relationship between the covariate (mildew) and the dependent (grain yield) variable, is

not significant, F (1, 27) = .107, p .746. This shows that there is no relationship (effect)

between the covariate and the dependent variable.


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W2=SSB -(K-1)MSW/ SST+MSW

SSB = SS (for independent variable), MSW (MS for error), SST (SS for total).

W2= 1.103-14(.006)/1.288+.006

=-0.79=(79%).

This means that the fifteeen barley varieties (the independent variable) account for

approximate 79% of the total variance in the grain yield (the dependent variable),

controlling for the effect of their mildew scores (the covariate). The main effect for the

independent variable (varieties) is significant controlling for the effect of the covariate

(mildew).

F (1, 27) = .107, p .746, W2 = 0.79.

Conclusion.

A preliminary analysis evaluating the homogeneity-of-regression (slopes)assumption indicated that the relationship between the covariate and thedependent variable did not differ significantly as a function of the independentvariable, , F (14,15) = .1.822, p = .130. The ANCOVA was significant, F (14,27) = .13.286, p < .001. However, 79% (w2 = .79) of the total variance in grainyield achievement was accounted for by the fifteen barley varieties controllingfor the effect of the mildew scores.





Corrected Model 1.128a 15 .075 12.679 .000

Intercept .143 1 .143 24.107 .000

VAR00008 .001 1 .001 .107 .746

Varieties 1.103 14 .079 13.286 .000

Error .160 27 .006

Total 8.705 43



The relationship between the covariate (mildew) and the dependent variable (grain yield), is

not significant, F (1, 27) = .107, p .746. This shows that there is no relationship (effect)

between the mildew disease and the grain yield variable.


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Varieties


Varieties

Mean Std. Error

95% Confidence Interval

Lower Bound Upper Bound

dimension1

Dore .039a .045 -.055 .132

2.00 .511a .046 .417 .605

3.00 .553a .052 .446 .659

4.00 .504a .053 .395 .612

5.00 .438a .046 .343 .533

6.00 .432a .044 .341 .523

7.00 .374a .045 .283 .466

8.00 .516a .046 .422 .610

9.00 .463a .045 .370 .556

10.00 .327a .045 .236 .419

11.00 .527a .045 .435 .619

12.00 .074a .045 -.019 .168

13.00 .440a .045 .348 .533

14.00 .620a .046 .525 .715

15.00 .402a .122 .153 .652

a. Covariates appearing in the model are evaluated at the following

values: VAR00008 = 1.4369.


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ANCOVA Output for Field 2009

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