Sunday, February 22, 2009

Thursday, February 19, 2009

comcast "agreement"

Comcast is the only provider of faster-than-dial-up internet in my area (that's right, no DSL). As such, they have a monopoly, and anyone who wants (or needs) to use the internet at modeRn speeds must do it through them. They just mailed a change in the "Comcast Agreement for Residential Services" along with the most recent bill. It contains this passage:
You understand that your computer or other devices may need to be opened, updated, accessed or used either by you or by us or our agents, in connection with the installation, updating or repair of HSI or video services. The opening, accessing or use of your computer, other devices used in connection with your computer, or your video devices may void warranties provided by the computer or other device manufacturer or other parties relating to the computer's or device's hardware or software. Neither comcast nor any its affiliates, suppliers, or agents, shall have any liability whatsoever as a result of the voiding of any such warranties.

Is it irrational for me to be disturbed by this?

Wednesday, February 18, 2009

playing cards

Cards are 52 rectangles of stiff paper, or cardstock decorated uniformly (to ensure indistinguishability) on one side, on the other, divided into four "suits" of thirteen cards each, numbered from two to ten, plus a jack, a queen, a king, and an ace.

Cards are randomized via a physical process called "shuffling," which can be realized via a number of techniques. Proper randomness is achieved by seven "shuffles."

Although a number of different games involving any number of players and cards (e.g. poker, "go fish") are possible, there is a long tradition of four player games, where each is dealt thirteen cards (i.e. a quarter of the deck). Usually, one suit is declared "trump" (i.e. it dominates cards of any other suit, no matter their value), and play proceeds as players lay down cards sequentially. Every four cards constitute a "trick" which one player wins and keeps for himself. Games in this tradition include whist, bridge, spades, and hearts.

I appear to be a member of the last generation for which the above is common knowledge. Casual questioning of average samples of those not ten years my junior reveals (i) the general assumption that card games are simply a subset of computer games, (ii) uncertain knowledge about the constitution of a deck, and (iii) a vanishingly small understanding of appropriate randomization procedures.

Sunday, February 1, 2009

theory and measurement

How does theory infect scientific observations? When are observations "theory-laden"?

One answer, obviously, is in terms of the interpretation of data, even in the subjective assessment of data.

A second answer, however, comes from the practice of measurement itself. Many quantities of scientific interest are difficult to measure directly. As a consequence, we must instead measure a proxy. The relationship between this proxy and the quantity of interest is purely theoretical. For example, Galileo's experiments rolling balls down inclined planes were an attempt to use height as a proxy for velocity in order to measure the effects of gravity (anachronous, but that's how we would put it today) near the surface of the earth. There was simply no direct way to make appropriately exact measurements of velocity.

A modern example: measurements of brain activity. When an fMRI scan is performed flow of blood to an area of the brain is a proxy for "activity" (as very loosely construed), which is itself a proxy for the real topic of interest, the modular role of different areas of the brain in complex mental calculations.