1

I am working on a mixed model using lmer in R and I am a bit stuck on some coding. I have measured male and female fitness in Drosophila from 35 inbred lines (genotype) over three blocks.

My response variable is 'fitness' with n=10 individuals/sex/line/block tested.

Sex is fixed, Block is random and Line nested within block is random. I primarily interested in the interaction between sex and line. Therefore my model looks like

m1<-lmer(FitnessCured~Sex+(1|Block/Line)+(1|Block)+(1|Sex:Line),noNAdata)

If I wanted to tested the significance of the Sex:Line interaction my plan is to just compare the above model to a model without the interaction and use anova to compare the two models

e.g. m2<-lmer(FitnessCured~Sex+(1|Block/Line)+(1|Block),noNAdata)
anova(m1,m2)

However what I am wondering is if I am testing the significance of the Sex:Line interaction (included as a random effect) will R know Line is nested within Block ???

How do I specify the interaction between Sex by Line nested within Block ??

Should it be something like

 m1T<-lmer(FitnessCured~Sex+(1|Block/Line)+(1|Block)+(1|Sex:Block:Line)   

Any thoughts would be appreciated. I have included a sample of my data below

     Block Line Sex FitnessInfected FitnessCured
2        1    2   M          1.4573       0.2215
3        1    2   M          1.1551       1.1379
4        1    2   M          1.4573       1.1379
7        1    2   M          1.4573       0.4108
9        1    2   M         -1.5648       1.1379
11       1    2   F         -0.2669      -1.2473
12       1    2   F          0.2785      -1.2473
13       1    2   F         -0.5396      -1.2473
14       1    2   F         -0.5396       0.4602
15       1    2   F          1.8237      -1.2473
16       1    2   F          0.7330       0.4965
17       1    2   F          1.5511      -1.2473
18       1    2   F         -0.5396       1.4774
19       1    2   F          1.0966       1.1868
20       1    2   F         -0.5396      -1.2473
21       1    3   M          1.2054       0.7162
22       1    3   M          1.2585       0.3146
24       1    3   M         -1.5648       0.2672
26       1    3   M         -0.8932      -0.8615
27       1    3   M          0.5047       1.1379
28       1    3   M          0.7704       1.1379
29       1    3   M         -1.5648      -1.7689
31       1    3   F         -0.5396       0.6782
32       1    3   F         -0.5396      -1.2473
33       1    3   F         -0.5396       1.0778
34       1    3   F         -0.5396      -1.2473
35       1    3   F         -0.5396      -1.2473
36       1    3   F         -0.5396       0.7145
37       1    3   F         -0.5396       0.7508
eoin.duff
  • 37
  • 2
  • 8

0 Answers0