This seems like an obvious assumption to make, but it isnt always true. It is easier to see why if you are measuring a single value multiple times in order to g

This seems like an obvious assumption to make, but it isnt always true. It is easier to see why if you are measuring a single value multiple times in order to get a more accurate estimate of the true value. In that case your "model" is simply the mean of all measurements made and can exceed the accuracy of a single measurement. In this case, the model is predicting values of multiple structures, but patterns could still theoretically be found which allow for predictions beyond the accuracy of a single measurement.