[R] analysis of circular data with mixed models???

2009-05-15 Thread Steven Van Wilgenburg
Hi.

I am trying to model data on movements (direction) of birds and the 
response variables are compass directions (0 to 360).

I have found two packages CircStats and Circular that can implement 
linear models for a circular response, which will do what I need for 
the data set I am currently working on (modeling movements for only 1 
species).

However, in the near future, I would like to extend my modeling by 
including multiple species, and treating each species as a random 
effect. It appears that analysis of circular data using a mixed model 
approach is possible (see the text Statistical Analysis of Circular 
Data, Fisher 1996); however, does anyone know of a package in R that 
implements mixed models for circular data?


Cheers

-Steve

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[R] error propagation

2008-02-08 Thread Steven Van Wilgenburg
Hello,


I wish to examine the influence of error in variables on my analyses 
via error propagation. I have a data frame (x) as follows:

id   response
1-121
2-131
3-125
etc.

I wish to propagate errors for each row in the data frame, where error 
is distributed around the value of the response variable. To do this, I 
wish to simulate 1000 variables for each row in the above data frame. I 
wrote the following, but suspect that it is not applying the function 
to each row

sim-rnorm(1000,mean=x$response, sd= (rnorm(1000,mean= 9.454398, 
sd=1.980136)))

Do I need to use tapply to have the function iteratively go through 
each row? 

Any advice would be appreciated.


-Steve

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and provide commented, minimal, self-contained, reproducible code.