how can i tell when a model is missing a drop? what is external model validation when compared to the coefficient of determination of a model, how large of a drop in the r value is significant? how to validate an experiment with new data how to test the validity of a regression model which method is used to validate a model how to validate a regression model what is the purpose of external model validation how to calculate the accuracy of a model by comparing them to the coefficient of determination for predicting why does it occur when a drop in the r_prediction2$ in a model is significant? how to find correlation coefficient for a new model how much variability is it if the model is not fit how to validate an external model when to use external model validation how to validate the model with a new data set why are external models necessary for validation how to validate a regression model how large is a drop in correlation in r how large is the drop in the r in the coefficient external model validation