I have reread the discussion of change in apartment vacancy rates and tried to tie that to the two graphs provided for this particular discussion and I find I am still confused. I think this an example of an "explanation" wherein the topic is considered obvious by the author but which is far from obvious to most readers. At this particular moment I think there is no error in the discussion/graphs on apartment vacancy rates, which is about all I care to say about it at this time.
My interpretation of the article is that overall the market situation for the sectors the REA invests in look reasonably good but there is reason to expect a lower return in the near term IF the economy does indeed go into a recession. This is intuitively obvious but the paper provides some explanation as to why this would be the case. I don't think this would surprise anyone who has followed the REA closely. If the recession does materialize, and it is of some substance and duration, then I would expect the account's returns would decline somewhat in accord as they did for the 2001-2003 interval wherein the average return was a bit less than 6%/year for the three years.
Ray