Begin with artist match and title match, but

• Begin with artist match and title match, but

• Title given in many forms, different languages
• Same title given to preliminary drawings, smaller copies, and similar paintings
• Picture date often missing, size given inconsistently

• Tried to match on picture date, picture medium, and size

• Presumption was artworks sold less than 5 times were the same, more than 5 times were different

• Sample size goes to 2,090