I've got a problem while trying to specify the 'right' nesting of the random effects of my dataset. The dataset registers hourly variations in temperature inside termite mounds: 1. Sampling was performed in four localities. 2. On each locality, ~20 termite mounds were sampled. 3. The temperature of each termite mound was registered every hour during a day. So, 24 data, per mound, in four localities. According to [this previous question][1], to study how temperatures changes within mounds and among localities, I drew my model as: Tmodel <- lmer(Temperature ~ Hour + Locality + (1|Locality/Mound/Hour), Tver, REML=FALSE) and I got this message: >Error in checkNlevels(reTrms$flist, n = n, control) : number of levels of each grouping factor must be < number of observations From this message, I get that I'm sort of 'constraining' my data, so that per grouping factor (hour, in mound, in locality), there is just one observation; am I right? But then, how should I specify the nestedness of my random factors? Many thanks in advance for your time and patience. Any tip of advice will be much appreciated. ANTÓN [1]: https://stats.stackexchange.com/questions/79360/mixed-effects-model-with-nesting