Massive chart fail from the Heritage Foundation which tries to show that the Affordable Care Act killed jobs by referencing the second derivative of employment.
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- The chart shows jobs/month. The text corresponds to jobs/month^2.Jul 21, 2011
- Gosh what am I missing? I don't see the text then.Jul 21, 2011
- I seriously had to look at it 18 times before I got it, and my last comment was not well-phrased.
So, the first chart is straight-up, jobs vs. time. The second chart is the first derivative - delta(jobs) vs. time. All good so far. But the text in red (67,600 and 6,400), that's actually the slope of the the line in the second graph, so, the second derivative, jobs/month^2.
(Did I say that right that time? I think I said that right that time.)Jul 21, 2011
- No, I still don't get it. The vertical axis, the one centered at 0 is in units of jobs, with some baseline value subtracted out. The horizontal is in units of months. The two slopes are unit-ed correctly.
No wait, I am wrong. Ah yes, that isn't a baseline, zooming in on the first graph. It is the first derivative of the graph above it. The 0 crossing of the lower graph corresponds in time to the local min of the upper graph.
Yep. Fail. Would have been better off to fit a parabola to the left half of the first graph and overlay an extrapolation on the first graph. At least from the purely "make your point with graphs" issue, aside from (a) and (b).Jul 21, 2011
- No, I think the vertical axis is jobs/month. There was never a date in American history where there were -750,000 people working.
Oh but you mentioned a baseline value. I think there is a possible reading where they subtracted the January 2010 value out for some reason, but this reading seems unlikely since I think it is generally accepted that during 2009 employment levels decreased.Jul 21, 2011
- Yeah it is not a baseline. The zero crossing is at the local minimum of the top graph. That's a sure sign that it is proportional to the first difference/first derivative. That's basically what I missed.Jul 22, 2011