He’s published a graph mapping “the percent of employed people who are members of unions” against FY2011 shortfall as a percent of the budget. Not the percentage of people employed by the public sector, but rather of all employed people.
I wanted to look at the relationship between unions and deficits more systematically. Like McCartin I used the CBPP data on budget deficits, although I focused not on the projected 2012 deficits but on the 2011 deficits (see Table 4 of the report). I do not know of readily available data on public-sector collective bargaining or on public-sector union strength, so I used the percent of employed people who are members of unions (from this BLS report).
To his credit, Sides writes:
If someone knows of better data on unions, please send it along. And, since this is an area in which I am mostly ignorant, cites to scholarly research are also welcome.
He seems to understand that the comparison he’s offering doesn’t tell us much of anything. I have been interested to see that other bloggers are trying to draw a broader conclusion from Sides’s graph, but I don’t think Sides should be held accountable for that unfortunate fact.