Boo 25-50

The primary research that this author does is quite incredible.  She is very dedicated to get the exact life and atmosphere of the culture that she is investigating.  I wonder, however, if all of her first hand research is 100% accurate.  Some of the time periods that are covered in this book last all night or for multiple days.  Does the author not eat or sleep?  Or is this a mere retelling of events that a slum-dweller is telling her?  I wonder how much time she actually spends in the slum observing, and how much of her time is listening to the people tell about their lives.  I remember in the author's notes her telling the readers  that she got some of the inhabitant's reactions after the fact, but the stories changed with time.  How accurate can these truly be if she was either not their or if the stories changed?