A model is supposed to predict a value that represents proportion, namely, the predicted value should be in [0,1]. However, model is just a linear regression, producing confidence intervals violating the boundaries of [0,1]. Of course it is not an adequate model. However, what is the statistical term to describe such symptom of a model, Namely, confidence interval violating physical boundaries of objects being modeled? If you could provide a reference, it would be highly appreciated!