Hipótesis: Están las frecuencuencias Dominante de F12 Khz explicadas por la estructura vertical, horizontal y área basal.

Cargamos paquetes:

library(lme4)
library(nlme)
library(MCMCglmm)
library(AICcmodavg)
library(mgcv)
library(MuMIn)
library(MASS)
library(lattice)
library(lavaan)
library(piecewiseSEM)
library(car)

Cargamos la base de datos:

load("F12.Rda")

Estructura de variables:

str(F12)
## 'data.frame':    34 obs. of  7 variables:
##  $ Site     : Factor w/ 36 levels "CE01","CE02",..: 1 2 3 4 5 6 7 8 9 10 ...
##  $ mean     : num  1310 189 476 363 683 ...
##  $ sd       : num  1102 436 797 636 731 ...
##  $ Frec_Dom : chr  "F12" "F12" "F12" "F12" ...
##  $ prom.vert: num  0.1421 0.091 0.1065 0.0828 0.0906 ...
##  $ prom.hor : num  0.0542 0.0601 0.0596 0.0586 0.0583 ...
##  $ AB       : num  20296 10729 11029 7827 15654 ...
##  - attr(*, ".internal.selfref")=<externalptr> 
##  - attr(*, "sorted")= chr "Site"

Estandarización de variables:

Site <- as.factor(F12$Site)
FDm <- as.numeric(F12$mean)
FD <- as.factor(F12$Frec_Dom)
Fv <- as.numeric(((F12$prom.vert)-mean(F12$prom.vert))/sd(F12$prom.vert))
Fh <- as.numeric(((F12$prom.hor)-mean(F12$prom.hor))/sd(F12$prom.hor))
AB <- as.numeric(((F12$AB)-mean(F12$AB))/sd(F12$AB))

Agrupación de variables transformadas:

data<- data.frame(Site,FDm, FD, Fv, Fh,AB )
attach(data)
## The following objects are masked _by_ .GlobalEnv:
## 
##     AB, FD, FDm, Fh, Fv, Site
mod1 <- lm(FDm~Fv+Fh+AB,data = F12)
mod2 <- lm(FDm~Fh,data = F12)
mod3 <- lm(FDm~Fv,data = F12)
mod4 <- lm(FDm~Fv+Fh+Fv:Fh ,data = F12)
mod5 <- lm(FDm~AB)
mod0 <- lm(FDm~1,data = F12)
AIC(mod1, mod2, mod3, mod4, mod5)
##      df      AIC
## mod1  5 467.8711
## mod2  3 475.6497
## mod3  3 476.1118
## mod4  5 479.0901
## mod5  3 468.0821
AIC(mod1, mod0)
##      df      AIC
## mod1  5 467.8711
## mod0  2 474.2632

No hay fuertes evidencias de que existe un mejor modelo.

#Comprobación de Supuestos
par(mfrow=c(2,2))
plot(mod2)

#Revizamos la ortogonalidad de las variables independientes

cor_PCA <- (princomp(F12[,5:6]))
biplot(cor_PCA)     

#Seleccion de variables a traves del método “backward”

step <- stepAIC(mod1, direction="backward")
## Start:  AIC=369.38
## FDm ~ Fv + Fh + AB
## 
##        Df Sum of Sq     RSS    AIC
## - Fh    1     74058 1478685 369.13
## <none>              1404626 369.38
## - Fv    1     96015 1500641 369.63
## - AB    1    576525 1981151 379.08
## 
## Step:  AIC=369.13
## FDm ~ Fv + AB
## 
##        Df Sum of Sq     RSS    AIC
## <none>              1478685 369.13
## - Fv    1    111140 1589825 369.59
## - AB    1    534648 2013332 377.62

No se muetsra una efecto importante para eliminar alguna variable

#Para la importancia relativa de cada variable del modelo

library(leaps)
attach(data)
## The following objects are masked _by_ .GlobalEnv:
## 
##     AB, FD, FDm, Fh, Fv, Site
## The following objects are masked from data (pos = 4):
## 
##     AB, FD, FDm, Fh, Fv, Site
leaps <- regsubsets(FDm~Fv+Fh,data = data, nbest = 10)
summary(leaps)
## Subset selection object
## Call: regsubsets.formula(FDm ~ Fv + Fh, data = data, nbest = 10)
## 2 Variables  (and intercept)
##    Forced in Forced out
## Fv     FALSE      FALSE
## Fh     FALSE      FALSE
## 10 subsets of each size up to 2
## Selection Algorithm: exhaustive
##          Fv  Fh 
## 1  ( 1 ) " " "*"
## 1  ( 2 ) "*" " "
## 2  ( 1 ) "*" "*"
plot(leaps, scale = "r2")

#intercepto y Fh explica 0.0056 de la varianza

#Autocorrelación

vif(mod1) #Si es menor a 2-4 esta bien
##       Fv       Fh       AB 
## 1.133011 1.032976 1.142911
sqrt(vif(mod1)) #Muetras la inflacion de de cada variable (entre 2 a 4)
##       Fv       Fh       AB 
## 1.064430 1.016354 1.069070
max(vif(mod1)) #Si es menor a 2-4 esta bien
## [1] 1.142911

#Relación entre variables

par(mfrow=c(1,3))
library(visreg)
visreg(mod1)

Modelo lineal generalizado:

glm1 <- glm((FDm+1)~Fv+Fh+AB, family=poisson, data=data)
summary(glm1)
## 
## Call:
## glm(formula = (FDm + 1) ~ Fv + Fh + AB, family = poisson, data = data)
## 
## Deviance Residuals: 
##      Min        1Q    Median        3Q       Max  
## -22.8911   -9.0653   -0.8553    5.2278   22.4665  
## 
## Coefficients:
##             Estimate Std. Error z value Pr(>|z|)    
## (Intercept) 5.845081   0.009441  619.12   <2e-16 ***
## Fv          0.171149   0.010058   17.02   <2e-16 ***
## Fh          0.136155   0.008813   15.45   <2e-16 ***
## AB          0.326198   0.008185   39.85   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## (Dispersion parameter for poisson family taken to be 1)
## 
##     Null deviance: 4999.7  on 33  degrees of freedom
## Residual deviance: 3471.3  on 30  degrees of freedom
## AIC: Inf
## 
## Number of Fisher Scoring iterations: 4
glm1quasi<- glm((FDm+1)~Fv+Fh+AB, family=quasipoisson, data) #Modelo de quasi, por la sobredispersión
summary(glm1quasi)
## 
## Call:
## glm(formula = (FDm + 1) ~ Fv + Fh + AB, family = quasipoisson, 
##     data = data)
## 
## Deviance Residuals: 
##      Min        1Q    Median        3Q       Max  
## -22.8911   -9.0653   -0.8553    5.2278   22.4665  
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  5.84508    0.09859  59.285  < 2e-16 ***
## Fv           0.17115    0.10504   1.629 0.113692    
## Fh           0.13616    0.09204   1.479 0.149481    
## AB           0.32620    0.08548   3.816 0.000631 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## (Dispersion parameter for quasipoisson family taken to be 109.0583)
## 
##     Null deviance: 4999.7  on 33  degrees of freedom
## Residual deviance: 3471.3  on 30  degrees of freedom
## AIC: NA
## 
## Number of Fisher Scoring iterations: 4