That is a true difference and I should have been clearer. I should have specified that I don't believe they used any test data, the "study" had probably been do

That is a true difference and I should have been clearer. I should have specified that I don't believe they used any test data, the "study" had probably been done with no test data set and simply using all data for the estimation of regression parameters. I believe that (1) the model made little "mechanistic" sense, (1) the forecasting accuracy of the model would have been low, (3) the model had good hind-casting accuracy through overfitting by modeling the "noise" in the data with too many predictors. (4) the model could have not guided any training.