I am trying to fit a curve on the data( in the attached image). I see that there is a lot of variance in the response variable for each explanatory variable value. I am not sure how to model this. I tried a polynomial curve(GAM) but at best it is explaining only around 10% of the data. I understand that this indicates that I need to add more variables to the model. However, I need to avoid going down that path.
I have tried transforming the explanatory variable but haven't found much luck. I know there is very limited things we can do with such distribution but just throwing it out to all the brilliant minds out there if some one has had to do something similar or if someone has some ideas I could try.
I have attached an image of the distribution as I am not sure how to attach a data file.
Let me know if I haven't provided enough information in my request and I will try to add more details.