Friday, March 27, 2015

Pinnacles, again

No condors this time, but a spectacular wildflower display, the emphasis on shades of blue and purple: abundant larkspur, shooting stars, and fiesta flowers. The unseasonably warm weather brought out a couple of snakes: a lazy king snake on the road coming in (photo courtesy AF), and a beautiful gopher snake near the Balconies Cave entrance.

Oh, did I forget to mention lichens?

Tuesday, March 24, 2015

The real cost of coal

I use James Stock and Mark Watson's excellent textbook in my undergrad econometrics class. Like all textbooks, it seems outrageously priced. But I'm happy to send a little business Jim Stock's way when he is so sensible and right on a pet topic of mine. All I would add to his "adder" (an extra royalty charge on coal to account for carbon) would be a further surcharge for mountaintop removal...
The greenhouse gas burden from coal taken from government lands can no longer be ignored. Using a carbon adder to increase the royalties that taxpayers receive is a sensible step in the right direction.

Monday, March 23, 2015

Landscape design...

... by pure dumb Darwinian luck, in the front yard... let me know if you want the plant list...

Sunday, March 22, 2015

Back to the Future, indeed...

As a 57-year-old suburban white dude, I can't be too hard on myself for being late to the party. D'Angelo and the Vanguard's Black Messiah is a bass-driven, overproduced, Prince-inspired feast for the ears from soup to nuts. I'm not sold on the well-meaning lyrics, but you don't need to pay much attention to the words if you just let that syncopated funky wall of sound wash all over you.

Saturday, March 21, 2015

More leafing out in Foothills Park

Black oak, big-leaf maple, maidenhair fern...

Friday, March 20, 2015

Springtime in New York

Reading the NY Times has become more than a little depressing, what with religious nut-jobs killing people right and left, and Mitch McConnell and Laurence Tribe just working their asses off for Peabody Energy and the rest of Big Carbon to totally fuck up our beautiful planet. But the Times also employs Joshua Bright, a photographer who can take the most cliched theme in the book and make some springtime magic from it...

Tuesday, March 17, 2015

Today's little epiphany

The worst possible case of omitted variable bias in estimating the causal effect of Z on Y would be if Z had no direct causal effect on Y whatsoever, but was highly correlated with Y entirely because of Z's correlation with some other confounding variable X that causes Y. Then the regression coefficient on Z would be nothing but omitted variable bias! But what if you changed your mind and decided you were actually more interested in the causal effect of X on Y? Then Z, of course, would be a perfect instrumental variable!