The curious case of 1982

Several months ago, Brendan Nyhan took issue with political commentators who were urging Obama to campaign more like Reagan.  Jon Judis, in particular, had argued that economic models in 1982 had predicted Republican House losses of around 50 seats, but Reagan's communications skills limited Republican losses to only 26.  Brendan argued that this was silly -- that midterm elections tend to turn on the fundamentals rather than the president's political skills.

Of course, I'm in sync with Brendan on this point, but when I look at my midterm data, I find that 1982 really was a significant outlier.  Below is a graph showing how the president's party did in every midterm election since 1950 relative to my forecast (based on growth in real disposable income and the president's popularity).  Each data point is the actual gain in seats minus the expected seat gain.  So positive numbers means the president's party did better than expected, even if they still lost seats.

Interestingly, 1982 is the biggest positive outlier in the whole series.  My model forecasts the Republicans losing 47 seats that year, but they only lost 26.  How did they pull that off?

Some possible explanations:

1. My model isn't very good.  In Brendan's post, he cites Alan Abramowitz' somewhat more complex model that pretty much nails Republican seat losses for that year.  So maybe my bias toward parsimony has some down sides. 
2. Related to point 1, Republicans held only 192 seats going into the 1982.  It's just hard to lose 47 seats when you only control 192 of them -- you're pretty much cutting bone at that point.  By contrast, the Democrats today control 257 seats, which necessarily includes some districts that aren't generally friendly to Democrats.  A modest Republican wave can take out a bunch of those. (Notably, when I include the number of seats held by the president's party, the forecast for 1982 drops from 47 to 33 -- much closer to reality.)
3. Maybe Reagan and the Republicans really did have a better campaign and communications strategy than Obama and the Democrats do this year.  Again, though, I doubt this -- both presidents were quite aggressive in trying to pin the economic failures on the previous administration.  What's more, Obama actually enjoys slightly higher approval ratings than Reagan did at this point in his first term.