I have a dataset of about 30 features, most of which are profile information of insurance customers. There are a couple features that are time-dependent (guess you could call it time series) insurance premiums. These premiums exhibit a trend of going up.
Due to certain constraints, my training dataset spans 3 years from 2013 to 2015, but missing data in 2016. I've trained a gradient boosting regressor to predict the ROI on these customers at the current time (2017). But as it is right now, there is a pretty big gap from end of 2015 to today. We know that the premiums have been going up during 2016 (actually more rapidly than what we've seen in 2015 and before). So my model is basically trained on old premiums and it led to underestimated ROI on current customers.
Putting that complication of more rapid growth of premium aside, if we assume that the trend before 2015 continues the same way to today, what technic can I use to incorporate this information into the model training?
I know one way to engineer a time-dependent feature is to use EWMA. But I suspect it won't help much with GBM model. Maybe I should try some other models like GLMM?