[R-sig-eco] Confidence intervals in lmer

[Chris Howden]

U could try the predict function with se.fit=true. I believe this
should give u the predicted score and se and u can calculate CI from
there.

U'll have to create an input matrix with the score u want to predict for.

Chris Howden
Founding Partner
Tricky Solutions
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On 27/09/2011, at 23:23, Adam Hayward <a.hayward at sheffield.ac.uk> wrote:

> Dear list members,
>
> I have a significant interaction between two continuous variables (it
> happens to be a mixed model in lmer, but I imagine the same is applicable to
> a glm). The interaction tells me that the relationship between z and y
> changes as a function of x, but I want to know whether y has a significant
> effect on z at a given value of x. For instance, the interaction might show
> that the relationship between body weight and fitness changes with age, but
> I want to know if the association between body weight and fitness is
> significantly positive at the age of 1. Therefore, I'd like to estimate 95%
> CIs or SEs around the association between body weight and fitness at a given
> age, but have yet to work out how to do it. Any suggestions would be greatly
> appreciated.
>
> Best wishes,
> Adam
>
>
>
>
> --
> Adam Hayward
> Post-Doctoral Research Associate
> Department of Animal and Plant Sciences
> Alfred Denny Building
> University of Sheffield
> Western Bank
> Sheffield S10 2TN
> UK
>
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>
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