Glantz-Culver line?

What is the Glantz-Culver line? I know that it predicts the outcome of a game (i.e. glantz-culver line for Team A vs. Team B in the NBA will be Team A by 1 1/2, or something similiar), but how does this prediction work? How do they figure out the predicted score, and what does the actual name "Glantz-Culver" mean? Is it the founder of this method?

Thanks, I'm just interested in understanding this