[R] Post-hoc tests on Split-plot design

Shah msnewaz at lakeheadu.ca
Wed May 13 21:24:27 CEST 2015


Hi Richard,
Thank you very much for your cooperation. I installed the packages "HH" and
run the following model: 

Bud.aov<-aov(terms(Budburst~CO2*SoilTemp*Photoperiod+Greenhouse/(SoilTemp*Photoperiod),keep.order=TRUE),data=data)
> summary(Bud.aov)
                                                  Df   Sum Sq   Mean Sq    F
value    Pr(>F)   

CO2                                            1    1465.2    1465.2      
109.612   < 2e-16 ***

SoilTemp                                     1    238.0      238.0        
17.805      3.60e-05 ***

CO2:SoilTemp                              1    145.7      145.7         
10.900     0.001125 **

Photoperiod                                  2    986.9      493.4         
36.914     1.62e-14 ***

CO2:Photoperiod                           2     0.2          0.1           
0.006        0.994095   

SoilTemp:Photoperiod                    2     14.6        7.3           
0.545        0.580893   

CO2:SoilTemp:Photoperiod             2    186.3      93.2           6.969       
0.001167 **

Greenhouse                                   2    75.5        37.8          
2.824        0.061538 . 

SoilTemp:Greenhouse                     2     5.9          3.0          
0.221        0.801896   

Photoperiod:Greenhouse                  4    283.4      70.8           5.300      
0.000433 ***

SoilTemp:Photoperiod:Greenhouse   4    56.7        14.2          1.060       
0.377363   

Residuals                                       216 2887.3    13.4



The results don't look like the results for the split-plot design which I
got using the model below: 

mod<-aov(Budburst~CO2*SoilTemp*Photoperiod+Error(Greenhouse/(SoilTemp*Photoperiod)),data=data)

> summary(mod)

Error: Greenhouse

              Df Sum Sq Mean Sq F value Pr(>F)  

CO2        1 1465.2  1465.2      38.81    0.0248 *

Residuals  2   75.5    37.8                 

Error: Greenhouse:SoilTemp

                      Df Sum Sq Mean Sq F value Pr(>F)  

SoilTemp         1 238.00  238.00   80.57       0.0122 *

CO2:SoilTemp  1 145.70  145.70   49.32       0.0197 *

Residuals         2   5.91    2.95                 

Error: Greenhouse:Photoperiod

                          Df Sum Sq Mean Sq F value Pr(>F)  

Photoperiod         2  986.9   493.4        6.965    0.0498 *

CO2:Photoperiod  2    0.2     0.1          0.001     0.9989  

Residuals            4  283.4    70.8                 

Error: Greenhouse:SoilTemp:Photoperiod

                                        Df Sum Sq Mean Sq F value Pr(>F)  

SoilTemp:Photoperiod         2  14.56    7.28        0.514    0.6330  

CO2:SoilTemp:Photoperiod  2 186.31   93.15      6.576    0.0544 .

Residuals                           4  56.67   14.17                 

Error: Within

                Df   Sum Sq Mean Sq F value Pr(>F)

Residuals 216   2887     13.37               


The F and P values are quite different. Moreover, I could not run the
post-hoc tests as well. At this stage I shall highly appreciate your further
assistance.

Thanks.

Shah                     



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