Given a sample of items with known monetary values, say 10 cars, and a person rating each car in turn as being more or less valuable than their own, what would be the best way of estimating the value of that person's car?
The rating that they choose could be more complicated than just less/more valuable - it could be, for e.g., 'Much less', 'Less', 'Similar', 'More', 'Much more'. Whatever necessary within reason to get an accurate estimate...