Explain This Regarding Publisher's Weekly Yearly Lists

[Markxxx]

I was looking through the Wikipedia at the top selling novelsper year as defined by Publisher’s Weekly

But the article states:

The standards set for inclusion in the lists - which, for example, led to the exclusion of the novels in the Harry Potter series from the lists for the 1990s and 2000s - are currently unknown.

What does this mean exactly? I can’t find out where it explains what the standards to be in the list are in the first place.

Any ideas?

Thanks

[mobo85]

As per Publisher’s Weekly themselves:

@Publisher's Weekly

AAP excludes Potter because of the way it measures industry sales. The organization takes actual sales from 81 reporting companies (including Potter publisher Scholastic) and then uses Census Bureau data to extrapolate sales for the entire industry. In the past, the inclusion of Potter has distorted growth (and, in non-Potter years, the decline) of the children’s category.

Other lists have dealt with the success of Harry Potter in an interesting way: due to the Harry Potter books remaining at the top of the charts, the New York Times had to create a separate list of bestselling childrens’ novels; and then had to separate that one into two lists- one for one-offs and one for continuing series- because Harry Potter kept hogging the top of the childrens’ list as well.