I'm not convinced by these figures.
For starters, the "study" was based on US sales only at 6000 outlets, and I've read that out of 2 million shipped Tabs, only around 350k went to the US. Source is here
- not sure why their figures don't add up, but I guess they are not including domestic Korean sales.
In addition, in the US, anecdotal evidence suggests (source: numerous XDA postings) that quite a few people are buying a Tab on one carrier, returning it near 30-days, and purchasing again on a different carrier. This is for a variety reasons, but mostly either cost (cheaper on another network) or functionality e.g. AT&T Tabs can be easily flashed to support 3G and voice, whereas T-Mobile, Sprint, and Verizon ones cannot.
It may well be that 16% are being returned in the US, but we don't know the reason why they are being returned, we can't draw too many firm conclusions from this.