One common concern with consumer surveys is that the respondents might not answer truthfully. Whether through unconscious bias or simple oversight, there's always a chance that data from a survey might not be as reliable as it would appear.
It looks like Neilsen may have identified one such set of unreliable data:
For Nielsen’s Children’s Books in the Digital World report, parents of kids 12 and younger were asked the format of the last book they bought for their children. Ninety-six percent of parents of children up to age 6 reported buying a print book, and 94% of parents of children 7-12 said they bought a print book. However, Nielsen’s Books and Consumer research on reported book sales shows that 25%-32% of children’s books were purchased as e-books in the first-quarter of 2014. So based on this data, parents aren't coming clean about their purchasing behavior, which suggests that they may be under-reporting their e-book purchases.
I don't have any data on specifically YA/kids ebook sales in relation to that category, but even in the absence of data I don't think they're wrong. I think parents are under-reporting the number of ebooks they buy for their kids, though I wouldn't go so far as to say that "parents appear to have a bias toward print".
Rather, I would bet that the discrepancy comes from a subconscious bias, or rather an oversight. I think more parents don't connect the act of paying for an ebook on their mobile device with that of buying a paper book - at least, not until they reconcile their checkbooks.
I don't think it's anything overt; if that were the case the parents wouldn't be buying ebooks, wouldn't you agree?
Why do you think parents are under-reporting the number of ebooks they buy for their kids?
image by by boltron-