Blind Shaft

Based on familiar scandals in China's mines, Blind Shaft is a raw Chinese film about two ruthless grifters who, by pretending to be the relatives of miners who die in "accidents" they've staged, collect money from the mine owners. Mines owners pay because the mines are operating illegally or with substandard safety.

An unsparing camera follows the two men and their next victim, an innocent 16-year old who's trying to earn money to get back into school or get the school fees for his sister.

In a karaoke type singalong in a brothel, one of the grifters selects "Long Live Socialism" on the karaoke machine. As the men start to sing one of the girls asks if he's a hick. He's singing the old lyrics? Old lyrics? The new lyrics (according to the subtitles) include "The capitalist came back with their American dollars."

In one of the nicer touches in the film, one of the men who has misgivings about this particular scam tries to give him a last good taste of life with session with a prostitute. The boy bolts, but later, by chance, meets her again at an office where both have goneto wire money home.

The very fact that the film got made speaks volumes about changes in China. There is no musical sound track. There are no special effects. The production values are low. The story seems to have been caught on home video and seems just as real. The depiction of the underclass and the relentless drive for money makes its case more than any proletarian socialist realism film ever could.

The Future of Textbooks is Colored Orange

This has been sitting in draft since May 25^th 2009.  In the interim the textbook rental market has taken off.  The references to the movie theaters, airlines, and credit card companies are still relevant as business are still nickel and dime-ing, "breaking out services", or scrambling to make up forlost revenue.

On the very first day of Stats the instructor asked who had purchased the book, where they got it, and how much they paid. One student said she rented her book on line from Chegg.com for ~$40. Others had paid over $150.

I took a look, rented the text on Wednesday, paid for expedited shipping, and, lo and behold, an orange box arrived via UPS on Friday. The book looks pristine. Amazing!

Chegg.com and the recent Credit Card Bill Of Rights legislation got me thinking about capitalism, movie theaters, and credit cards. It seems that credit card companies cannot make money on people like myself who pay their bills on time in the same way that supermarkets can't make a profit from me because I've never left the impoverished graduate student mentality behind.

Credit card services provide an exceptionally useful service by minimizing the need to use cash for transactions and speeding commerce. If I had to pay for the textbook by check I would not have gotten the textbook anywhere as quickly as the check winged it's way to the vendor and being routed through the banking system. Add on the delay of a weekend and I would be half way through a summer course without the book unless I forked over considerably more money.

If the credit card companies are making money, they're not making money on me.  Someone else is taking up my slack. Thank you, but is it fair? It is analogous to the movie theater owners who can't make money on what is ostensibly their business: showing movies. I'm told that their profits come from the (overpriced) concessions.

(It was not always thus. Back when I was an undergraduate, someone obtained a large brown paper sack of popcorn. I was told that the sack was what theater owners poured into their popcorn machines. The popcorn machines in theaters only warmed the popcorn.   The machines didn't actually pop the popcorn. (It was one of many myths shattered in college.) I remember bringing the sack into the theater with about half a dozen others. The kid with the sack sat in the middle seat in the second of 3 rows with the sack extended lengthwise so it overlapped the seat of the guys next to him. We punched a hole in the top side of the bag at either end and in the middle so all of us could reach in for popcorn. Nowadays, something like that could only happen at free films.)

In this regard what is fair? Am I taking unfair advantage of the poor credit card companies, enjoying the good life financed by the wretched of the earth who can't manage their credit or driven in desperation to borrow at exorbitant rates? (Will Jesus not drive these money lenders from the temple?)  Could be.  On the other hand, by taking advantage of the situation I'm revealing flaws in the business plans of the credit card companies thus strengthening the capitalism's Darwinian imperative. (The Cato Institute is invited to donate to my PayPal account.) Or helping to destabilize evil Capitalism. (Surviving members of the International Communist Conspiracy are invited to donate to my PayPal account.) Or playing into the hands of the Capitalist masters so they can appeal to their government lackeys to use legislation to save them from the proletarian onslaught when their profits tank. (Whoo. the 60's are coming back with a rush!)

Is there a sensible way of viewing the situation?  I always considered credit card purchases as a short term, no interest loan. In my days of impoverishment (make a note: not a bad title) I would keep a mental tally of what I owed. I was fortunate enough that I didn't need to cover a large unexpected medical bill. Are the frequent flier miles programs essential for their business or a marketing idea come back to bite airlines? Does the need to offer inducements or grow their market by extending credit to those who can't repay the total represent a flawed business model or have credit card companies found themselves caught short like Long Term Capital Management: strategies which worked well during "normal" economic times fail disastrously in times of upheaval.

Statistics - Aaarrrggghhhh!

My knowledge of statistics is embarrassingly poor. I've a layman's sense of what variance, covariance, and standard deviation means. The calculation part is simple. Understanding when to apply a measurement (1-tail, 2-tail, general linear model) and the significance of the result is beyond me.

I can usually skate by with just this, but I created a program which, among other things, calculates Cronbach's coefficient of alpha. From my readings, Cronbach's alpha is not a statistic, but a measure of internal consistency. As an example, does the overall exam grade reflect the overall question grades? Described as a measure of internal consistency, as I understand it alpha let's you see how the the variations on individual questions compare with the variation of the entire exam. (I've been told that the coefficient of alpha was really designed to be used on Likert scales, e.g., scales from excellent to very poor, rather than on test scores, but I'm having enough trouble wrapping my mind around the concept that I'll agree with anyone who purports to know what they're talking about.)

Onward.

I recently volunteered to analyze the stats of a recent survey figuring that I'd learned something in the process. What I learned was that the survey was not constructed well, that there was no universally accepted way of analyzing the survey, and I needed to know more about stats.

The statisticians were uniformly kind and most enjoyed themselves richly making derogatory comments about the people who constructed the survey. I could smile because I had nothing to do with creating the survey.

In the end, only one of several important questions on the survey yielded a significant result if you made certain assumptions about the responses: instructor's teaching distance learning courses seemed to think that the size of the classes they taught were appropriate. (The reason the results are questionable is that there was no indication that the instructors were answering questions about the same type of class(es).)

But that's not why I started this post. I had rewritten an Opscan/Scantron grading program and all the stats but Cronbach's Alpha worked out correctly. We know that only one instructor actually checked those statistics, so I was able to let that slide citing the press of other work. It looks as though I'll have the time now. So...

Always one to shirk duty, but having used up all my excuses, I searched the web for information about Cronbach's coefficient of alpha and was disappointed to find that the example on the NIH's web site had an error. The bleeping National Institute of Health! Sigh. Double check me: Table 18-2. Number of Teeth in the Sex Comb on the Right (x) and Left (y) Legs and the Sum of the Two (T) for 20 Drosophila Males contains an error. If you've got a moment, find the average value of column labeled x. The total of 20 numbers comes out to 133 with an average of 6.65 by my calculations. The illustration shows the average to be 6.25. The error seems to have escaped the authors and reviewers because the value of 6.65 is used about a quarter way down the page in the calculation of cov xy. The book, should you be inclided to investigage is Modern Genetic Analysis by A. J. F. Griffiths, W. M. Gelbart, J. H. Miller, R. C. Lewontin published by W. H. Freeman and Company (1999) ISBN 0-7167-3118-5.

I'm off to find another reference which will show me how to calculate Cronbach's alpha. Alternatively, maybe I can convince people that they don't need alpha calculated. Most instructors just look at the grades. Only one instructor actually looked at the kurtosis values, but then he was a Psych prof and measurements was his specialty.