Lack of Variation in Slopes
On 13-09-17 09:18 AM, AvianResearchDivision wrote:
Ben, What are the chances that there is absolutely no variation in slopes? This seems beyond unlikely, but is probably rooted in my limited understanding of what the model is actually doing. It seems you would always expect some sort of variation, even if it is the smallest amount. Maybe I am misinterpreting what this means. Anyways, thank you very much for taking the time to answer my many questions up to this point. I do very much appreciate it. Jacob
It's not that there is no variation; it's that the maximum likelihood estimate is that there is no variation. This happens a lot in mixed models, especially when the variance is small or the data set is small or noisy. See e.g. http://rpubs.com/bbolker/4187 [cc'ing back to r-sig-mixed-models ]
On Tue, Sep 17, 2013 at 9:06 AM, Ben Bolker <bbolker at gmail.com> wrote:
AvianResearchDivision <segerfan83 at ...> writes:
[snip]
You were spot on with your suggestion. Thank you very much for your
help.
I had mentioned before that I probably should keep random slopes within
my
models since that is a primary interest of my study, regardless of
whether
a LRT suggests they are needed. Would you still recommend keeping them within the model? Jacob
I don't think it will hurt.
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