How to determine the fixed and random effect using linear mixed effect model in R studio?

Hi all,

I would like to investigate the variation of eye size among species and among type using linear mixed model.
However, I am a little bit confuse to determine whether to be random effect and fixed effect. I tried to use this model: lmer(Eyesize ~ Species + (1|Type) in R studio

this is my code


example_data <-read.csv("EXAMPLE 1.csv", h= TRUE)
result = lmer(Eyesize ~ Species + (1|Type), data=example_data)

You can get my data here: data

I got the result of analysis like this

I cannot get the analysis result for species A.
Could anyone help me about this?
I cannot determine the fixed effect and random effect in this analysis.
I need help.


I'm not sure whether this helps, but in the fixed effects model the intercept is the fixed effect for group A.

does it mean my formula was wrong?

Not wrong. You have three groups and you estimate three parameters.

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