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I have an R data frame, set up like so:

Site Year Species Total_Observed
A    2000  Bird_1    4
B    2000  Bird_1    2
C    2000  Bird_1    9
A    2000  Bird_2    0
B    2000  Bird_2    1
C    2000  Bird_2    3
A    2001  Bird_1    7
B    2001  Bird_1    2  etc

And it goes on like this for some time. Lots of data, multiple sites, over many years. I'd like to do some kind of regression to see whether bird_1 is increasing over time in the same areas that bird_2 is decreasing over time, but I'm not sure how since this is partly a geospatial problem and it seems to me that bird_1/bird_2 observations can't be averaged due to their correlation by site. How do I approach this problem?

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Are the sites connected to each other, or can you neglect spatial interactions ? If you can neglect it, just start with fixed effect models with time and site dummies (plus a variable with the other kind of birds). If not, look at spatial regressions.

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  • $\begingroup$ Thank you! These sites aren't connected to each other, so I think I can neglect spatial interactions. I'll take a look at fixed effect models. $\endgroup$
    – aeiche01
    Commented Jul 21, 2019 at 17:48

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