This finally worked, thank you very much for your help! It was the two numbers in the shape option, as well as pymc’s math operations being necessary, that were evading me.
Now python keeps crashing for me when I try to run the model, but I figured it was because of the large number of variables my data has, and I have managed to run the model with 40/270 variables (that being the limit). Do you have any advice, or resources you could point me toward, on running pymc3 with large data, since I heard NUTS can supposedly handle hundreds of variables?