This post provides an excellent example of the inner workings of a mixed effects model: http://emhart.github.com/blog/2012/11/16/making-sense-of-random-effects/
In a hypothetical study, I have measured the wing length of a bird species at 10 different locations:
df <- data.frame(wing.length=rnorm(30),
location=paste('location', rep(1:10, 3)),
county=paste('county', sort(rep(1:3, 10))))
First 15 rows of dataframe:
wing.length location county
1 29.29024 location 1 county 1
2 30.06387 location 2 county 1
3 27.72127 location 3 county 1
4 29.74502 location 4 county 1
5 29.85506 location 5 county 1
6 30.26669 location 6 county 1
7 30.58748 location 7 county 1
8 30.47608 location 8 county 1
9 31.86882 location 9 county 1
10 28.87578 location 10 county 1
11 30.00726 location 1 county 2
12 30.52488 location 2 county 2
13 30.64339 location 3 county 2
14 29.93695 location 4 county 2
15 27.86217 location 5 county 2
However, unlike the mixed effects model in the linked blog post where each individual is measured 5 times, each location is only measured once.
In my hypothetical example, should a type of mixed effects model be applied, or would a two-way ANOVA be more appropriate? If a mixed effects model is needed, then what type?