> # Compare GLM (normal error assumed) 
> # to GzLM (normal error specified)
> # Limpet respiration data from Rohlf in Sokal and Rohlf
> #General Linear model, hence gaussian error
> RespModLM<-lm(VO2~Sp*Sal, data=SRBX11_2)
> summary.aov(RespModLM)
            Df Sum Sq Mean Sq F value  Pr(>F)   
Sp           1   16.6   16.64   1.463 0.23293   
Sal          1   84.8   84.76   7.453 0.00908 **
Sp:Sal       1   21.6   21.58   1.898 0.17531   
Residuals   44  500.4   11.37                   
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
> #Generalized linear model, error specified
> RespModGLM<-glm(VO2~Sp*Sal, family=gaussian, data=SRBX11_2)
> summary.glm(RespModGLM)

Call:
glm(formula = VO2 ~ Sp * Sal, family = gaussian, data = SRBX11_2)

Deviance Residuals: 
    Min       1Q   Median       3Q      Max  
-5.0996  -2.5611  -0.4571   2.8248   7.7854  

Coefficients:
            Estimate Std. Error t value Pr(>|t|)
(Intercept)  8.87708    5.86148   1.514    0.137
Sp           3.75000    3.70712   1.012    0.317
Sal          0.03345    0.07541   0.444    0.660
Sp:Sal      -0.06570    0.04769  -1.378    0.175

(Dispersion parameter for gaussian family taken to be 11.37332)

    Null deviance: 623.41  on 47  degrees of freedom
Residual deviance: 500.43  on 44  degrees of freedom
AIC: 258.74

Number of Fisher Scoring iterations: 2

> #Compare outputs
> anova(RespModLM)
Analysis of Variance Table

Response: VO2
          Df Sum Sq Mean Sq F value   Pr(>F)   
Sp         1  16.64  16.638  1.4629 0.232927   
Sal        1  84.76  84.760  7.4526 0.009075 **
Sp:Sal     1  21.58  21.582  1.8976 0.175310   
Residuals 44 500.43  11.373                    
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
> anova(RespModGLM)
Analysis of Deviance Table

Model: gaussian, link: identity

Response: VO2

Terms added sequentially (first to last)

       Df Deviance Resid. Df Resid. Dev
NULL                      47     623.41
Sp      1   16.638        46     606.77
Sal     1   84.760        45     522.01
Sp:Sal  1   21.582        44     500.43
> #Specify Type II SS for standard ANOVA table from GLM routine
> Anova(RespModLM, type=2)  
Anova Table (Type II tests)

Response: VO2
          Sum Sq Df F value   Pr(>F)   
Sp         16.64  1  1.4629 0.232927   
Sal        84.76  1  7.4526 0.009075 **
Sp:Sal     21.58  1  1.8976 0.175310   
Residuals 500.43 44                    
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
> Anova(RespModGLM, type=2)
Analysis of Deviance Table (Type II tests)

Response: VO2
       LR Chisq Df Pr(>Chisq)   
Sp       1.4629  1   0.226469   
Sal      7.4526  1   0.006335 **
Sp:Sal   1.8976  1   0.168343   
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
> # Note difference in p-value for Salinity
> # Calculate LR
> SpLR<-exp(1.4629/2)
> SalLR<-exp(7.4526/2)
> SpLR
[1] 2.078092
> SalLR
[1] 41.52518
> # SpLR < 20
> # 20 < SalLR < 100