I did not know that they use NPD numbers for internal documentation and calculation of sales. Would that not open the possibility of error in the number of copies sold since (as mentioned before) NPD does not get data from all major retailers. Is there an article or document which show (in some manner) that they use NPD numbers or is it just generally understood that NPD numbers are used?
I also find in hard to believe that Europe and other parts of the world would buy Harry Potter in numbers so much higher than America, therefore somewhere there either is an error in calculation of copies sold or we are underestimating sales by a wide margin.
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I did not know that they use NPD numbers for internal documentation and calculation of sales. Would that not open the possibility of error in the number of copies sold since (as mentioned before) NPD does not get data from all major retailers. Is there an article or document which show (in some manner) that they use NPD numbers or is it just generally understood that NPD numbers are used?
I also find in hard to believe that Europe and other parts of the world would buy Harry Potter in numbers so much higher than America, therefore somewhere there either is an error in calculation of copies sold or we are underestimating sales by a wide margin.