
Dear R community,
 
I am wondering what experimental design I am dealing with? I study the effect of daily air temperature on daily body temperature of the overwintering turtles (i.e. sleeping in soil). The model is a cosine wave with the air temperature as a covariate. 
 
Objects are 19 overwintering turtles. Daily body temperatures were measured for 9 turtles in 2005, 6 turtles in 2006 and 4 turtles in 2008. The turtles were different in each of these years, except for two turtles that were studied two years in a row. The study area (a small forest patch) was the same during these three years. Turtles usually would find some comfortable plots to overwinter in soil within the study area. Therefore, the overwintering plots differed between the turtles and between the study years. 
 
My big concern is if there is a spatial correlation between the three study years that we should take into account, since the study was done within the same forest area (but in different plots)?
 
Is that correct to treat the study years as a random effect? 
 
I also understand that I should incorporate autocorrelation model to account for daily variations in turtle body temperature. 
 
Thanks,
Julia
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