[R] installing package lme4

I am hoping to run a generalised linear mixed effect model but I don't seem to have access to package lme4. library (lme4) Error in library(lme4) : there is no package called �lme4� I'm unsure of how to go about installing this package and I haven't been able to find much online either. I a

[R] ANOVA test to decide whether to use multiple linear regression or linear mixed effects model

R-help: I am trying to decide between using a multiple linear regression or a linear mixed effects model for my data: model1 <- lm (responsevariable ~ predictor1 + predictor2 + predictor3 + predictor4, data= data) model2 <- lme (responsevariable ~ predictor1 + predictor2 + predictor3 + pred

[R] Tukey tests in two-way ANOVA

R-help: I'm looking into the abundance of an algal species over site and years using a two-way ANOVA: > summary (aov (fserratus ~ site+year)) Df Sum Sq Mean Sq F value Pr(>F) site 1 1487 1486.6 6.094 0.0155 * year 1 1173 1172.8