1 In regression models, error caused by variance in modeling which of these? can be attributed to phenomena inherent to the process being modeled that are impossible to be explained by the input features 2. can be due to the fact that, although it is possible to estimate the best possible parameters for a given data (i.e., the parameters can be very specific), the model will have trouble explaining new data 3. can happen when the best model parameters are hard to estimate, and thus the model is not too specific