Original: A larger study started later by Franciszek Piper used timetables of train arrivals combined with deportation records to calculate 960,000 Jewish deaths and 140,000-150,000 ethnic Polish victims, along with 23,000 Roma and Sinti (Gypsies).
Simplified: Around the same time, Franciszek Piper used timetables of train arrivals and other records of sending out of people by the Nazis. He calculated 1.1 million Jewish deaths and 140,000-150,000 Polish victims, along with 23,000 Roma (gypsies).