Obvious candidates
include Tumblr, Pinterest, Instagram. I don’t use any of them except to dabble, so I don’t know their strengths. Possibly Twitter or Facebook?
Obvious candidates
include Tumblr, Pinterest, Instagram. I don’t use any of them except to dabble, so I don’t know their strengths. Possibly Twitter or Facebook?
Wired has a good article on fires from “hoverboards,” which are essentially very small hands-free electric scooters. Here is an example. Start at about the :30 mark to see how these devices explode, and can easily set a house on fire.
I have some experience with the underlying cause of these fires, their Lithium-based batteries, because I use them in radio controlled aircraft. Fires of these batteries are not common, but they happen. Two people in San Diego who I know directly have had major fires. One lost a 2-unit condo, the other a detached workshop. The second one happened to an expert in RC flying!
One contributor to the A320 crash off Brazil in 2009 (Air France 447) was that the two pilots were making opposite inputs on their control sticks. The aircraft was in a stall, and therefore it was crucial to push the nose down, to regain airspeed. The instinctive human reaction (of untrained people) is to pull the nose up, since the airplane is falling. To oversimplify a long sequence of events drastically, pilot made the correct move, but the other pilot apparently panicked, and pulled back on his control stick. He continued to do this as they fell from 40,000 feet all the way to the Atlantic Ocean.
A new accident report says that the same thing happened in the crash of an Indonesia AirAsia Airbus A320, flight QZ8501, last year.
I was teaching the Virginia Mason VMMC case in Tech & Operations Management yesterday, and made a loose comment about busy urban hospitals being better than suburban ones. For example in the UC San Diego system, when someone is my family is really sick I try to take them to the downtown (dilapidated, overcrowded) UCSD hospital before I’d go to the one near campus (hotel-like, luxurious).
A student asked “why”, forcing me to do a little research. Here is my answer to her. Continue reading
When faced with lots of variables and likely interaction terms, is linear regression usable? In the comments, I get educated that yes, it can be done. Thanks to Nigel Goodwin. I will still tell my students to try some inherently nonlinear methods, though.
Source: Logistic Regression Vs Decision Trees Vs SVM: Part I
With the new A9 and A9X chips in its iPhones and iPads, Apple has mobile chips that are better than Intel’s. In fact Apple’s chip business is a very impressive technology story. I don’t have time to put together a full analysis, but I have collected some recent articles. 
Many sources are suggesting that Apple’s current chip generation (A9 and A9X) is better than Intel’s in low-power (mobile) performance. I guess it’s not news that Intel is behind Qualcomm in mobile, but I still find it surprising that Apple’s own chips are apparently better than X86 for Macintosh low-end laptops!
Some recent analysis paid for by the Department of Energy claims that the benefits of weatherizing homes are many times larger than the cost. In contrast, a careful Randomized Controlled Trial of a specific program comes to the opposite conclusion.
Recently, we conducted a first-of-its-kind, randomized controlled trial of the nation’s largest residential energy efficiency program, the federal Weatherization Assistance Program (WAP). The trial consisted of a sample of more than 30,000 WAP-eligible households in the state of Michigan. Our research revealed that investments in residential energy efficiency upgrades among weatherized households in our study cost about double what these households will save on their energy bills (efficiency retrofits cost about $4,600 per household and estimated energy savings are only $2,400). You can read more about our results here.
Sadly, my reading is with the Berkeley authors. The DOE studies seem to be grabbing all kinds of hypothetical benefits out of thin air. This does not mean that all such investments are under water, just that the average investment is not worth doing.
There are certainly ways to tighten/redesign any conservation program to make it more cost effective. But this requires an attitude of continuous investigation and improvement – not something that government agencies are good at. Once an agency has gotten money and gone ahead with a project, its incentives are to tout its benefits much more than to improve on the original design. This comes down to Congressional (and press) oversight. Any signal that the past project might have been less than ideal will be leapt on by political opponents. In my view, this set of incentives is one reason that so many government programs are weak, and furthermore do not improve over time.