Hi Chris

Is this censored regression? In which case R packages censReg (https://cran.r-project.org/web/packages/censReg/vignettes/censReg.pdf) or AER (https://stats.stackexchange.com/questions/149091/censored-regression-in-r) look like they will handle it.

Wish I knew the story about the upper limit on quoted price.

According to https://stats.oarc.ucla.edu/r/dae/tobit-models/ the speedometers in American cars in the 1980s weren't allowed to read more than 85 mph, so  if you wanted to predict maximum speed from engine size and weight, and could only use the speedo' to measure maximum speed, the data would be truncated.

Duncan

I have constructed an assignment for my Business Analytics course using the Diamonds data set in the ggplot2 package. Unfortunately, I have just realised that the y-variable, price, is truncated for some reason at about k$18.9 see HERE for a plot. There is nothing in the documentation of this data set that explains its source or the reason for truncation.

I guess I have two questions.

• Is anybody familiar with this data set and the true story for why it is truncated? (I can easily write my own story).
• Is there an standard linear model package that will estimate a regression where the Y-variable has a hard known truncation (let’s assume the observed y is conditional on Y<c). I am kind of embarrassed that I never encountered a truncated regression before