Yah, but the author is just referring to prior work. I skimmed this real fast last night, and like so much social science writing, there are lots and lots and lots of words, and not much of what I would call data. I've learned one simple thing about reading science papers: Look at the figures first, because that's the DATA. And there aren't many figures in this! But:

1. This work shows 11.5% of female Canadian students are on SA!  That is simply incredible.

2. Currently, SB's are 65% of SA membership, --male-- SB's are 15% (that was a surprise to me!), sugar mommas are 1%, while SD's are 18%. So the all important SB/SD ratio is roughly 68/15= 4.5.  

3. The longitudinal data (ie, time dependent) shows an interesting trend. 205,400 SB's and 22,200 SD's in 2012, a ratio of  9.25, while in 2017 the SB's had increased to over 509,000, but the SD membership increased faster, to 115,000, the ratio fell to 4.5. So, it is still a buyers market, but it used to be even better.

Some of the general conclusions are interesting. The author emphasizes that SB's tend to define themselves as what they are NOT. "I'm not your girlfriend", "I'm not an escort", "I'm not a prostitute", "You're not my boyfriend", "I have my own life". They use euphemisms  to separate themselves from sex workers, and they play mind games with themselves to preserve that distinction. How many times have we all heard this? Interestingly, the mind games weaken their bargaining position because they are then forced to frame the relationship (at least partly) in traditional romantic/courtship terms rather than purely commercial/transactional terms, leading to a negotiation that favors the SD's. That rings true to me, for even the semi-pros I've encountered on SA still had some subconscious motivation to assert "I am not a prostitute".

The author should have interviewed some SD's! That is the major falling to this thesis; it only has half the story.