Whine, whine, whine. I made large triangles because I wanted them very visible at even a momentary glance (which is all you often get in blogging). The centerpoints are located correctly, but were handplaced on top of the original graph, so as to underscore the point that I was using the Obama teams' actual data.

BTW I don't think anybody, ever, in the history of plotting data, ever, ever considered placing the hot point of the triangle anywhere but the center. So I'm not sure why you were feigning confusion on that issue.

Personally I prefer more rigorous-looking graphs, but I've got to say: this graph was linked by everybody (Instapundit, Hot Air (twice), Michelle Malkin (twice), AoSHQ (twice), PowerLine, The Corner, etc.). My latest plot, which took two orders of magnitude more work and has a very traditional Excel technical presentation, has gone nowhere.

Lesson learned: I think I'll stick to large triangles henceforth.

The underlying graph comes from Obama's own team. I suspect they used Excel07. The abscissa is, as you say, bizarre, but comparing it to historical data led me to believe that the labels on the abscissa are at the beginning of each quarter. That's why the data for the end of March is at the mid-point of the labels for the 1st and 3rd quarters. The point for April then lies 2/3 of the way between the 1st and 3rd quarters.

Any other interpretation would move the markers to the left, which would make the Obama teams' predictions look even worse.

Look dg – you reject anything you don't understand as being illegitimate economics because you presume nobody else can understand it. I'd be a little more circumspect about accusing other people of having nothing good and worthwhile to say.

And while those of us who have been around economics for any length of time didn't need Roberts to point that out to us, the undergraduates and newcomers to economics that he instructs may have. So, he did his job, and did it well. Thanx and congratulations for that, whether the fakers like it or not.

And, Faker No 1, you had your chance, and blew it, so crawl back in your hole.

And, Sonic Charmer, what I meant was that, if I don't know what you're talking about, I doubt that very many other people do, and that, if you really want to communicate with others, you'd better find a better way to do it.

Is that how you're going to change the world?

dg lesvic,

I don't know what you're talking about.

This argument you love to make always reminds me of a great Keynes line:

"Economists set themselves too easy, too useless a task if in tempestuous seasons they can only tell us that when the storm is long past the ocean is flat again."

Sometimes you have to get your hands dirty to do something useful, dg, and sometimes that requires math.

Predicting unemployment six months to a year in advance is like predicting weather six months to a year in advance. The economy and the weather are both a complex system. We shouldn't get so hung up on this graph, which the administration was really obligated to produce in some version or another – and pay more attention to monthly BLS unemployment projections. If those are consistently higher or lower than actual unemployment rates, that's far more disconcerting.

I've been in economics for half a century, and I don't know what you're talking about.

Is that how you're going to change the world?

The fact that the data are public and well-known argues for less not more potential ambiguity in interpreting things like 'what the triangles mean'. Since you know the data so well already, all you had to do was cross-check the triangle locations against what you know to be the data. You wouldn't have had to write this post at all.

The problem is fundamental–we don't have 2009 Q2 figures and won't have them until the first Friday in July.

That's not a "fundamental" problem. The author has taken the April report and overlaid it on a graph that (you are correct) otherwise plots data biquarterly. Unless you're saying the April release somehow connotes something fundamentally incompatible with what the quarterly releases represent, there's no "problem" here at all.

On clarification your objections are even odder than I'd first kenned.

Keep up that great work, and let Trumpet go blow his horn somewhere else!

My late father once read "The Hite Report" which was a bestseller on the latest findings on female sexuality. He told me that he had a math phobia from a young age, and that he was unable to understand the graphs and charts in the book, so he simply skipped them. Good math skills are useful and fun. Be happy you have them, and can use them profitably in your chosen profession.

I give the source in a link just before the link to his comments.

No one has to contact that source. The data are public and well-known. The problem is fundamental–we don't have 2009 Q2 figures and won't have them until the first Friday in July.

Why was it Robert's or Lesvic's or anyone else's obligation to chase down Mankiw for clarification, when it was his obligation to be clear in the first place, and, obviously, he had no intention of it?

Or was he just that incompetent?

That's definitely not Excel's default theme… I was wondering the same thing though, which software is responsible for those atrocities?