Wednesday, June 27, 2012

Doubles are sufficient for all data relations

I was interested a while ago in RDF, which stores information in triples, like "the sky" -> "has the color" -> "blue". I think there's too much structure in the triples structure. This can all be reduced to doubles, or just a simple directed graph, through judicious use of blank nodes. So the example becomes "the sky" -> blank node that could be interpreted as having-a-property, that blank node -> "has the color", that blank node -> "blue". (If you want you could add "has the color" -> "relation" and "blue" -> "property" or similar.)

This is of course not necessarily the most efficient way to store information, or the easiest to work with, but it reduces the structure so that all the primitives are of the same type, and I don't think that the structure can be simplified any further, so in that sense it represents a kind of absolute in data structuring.

I don't know what this kind of data structure is called by others or if there is any existing work around it. I would like to know!

Thursday, June 7, 2012

How hiring works now

The problem with the job market is not that there aren't enough jobs, it's that the jobs there are can't be done by enough people. What unites them is not even that they are technology jobs; many are visual design jobs that happen to use technology. I think what really unites them is that they are habits-of-mind jobs. They are jobs for people who spontaneously do and make things - not to fill up a resume, but because they are naturally active, productive people.

Anyway, a lot of people are hiring these days. Here's a bit from a notice I saw on an email list, with my comments:

1. Do not send us a resume. Please. Don't. We won't read it.
I'm so glad other people are starting to agree with me about this. Resumes are awful.


2. Email us at ////// at /////////////.
I remember a time when teachers told me I had to go buy resume paper to print my resume on. Now most people are understanding that email is how people communicate. I'd like for companies to be required to disclose whether they have a fax machine - so I know which companies not to invest in.

3. Tell us about yourself; your hopes, dreams, desires or, better yet, how you like to code.
I like all of these, but especially the response to that last bit would tell you a lot about whether a person actually knows anything.

4. Send us examples or your work: code snippets, urls, github, etc.
This is the main point, I think: What matters is what you've done. I don't care if you aced every course at Harvard and MIT and have a recommendation from Obama. Show me what you do. I don't know that portfolios are always appropriate at every stage in education, especially because it's at least as bad as resume-focus when people focus on portfolio-stuffing.

5. Be prepared to Skype with us!
Duh.

Tuesday, June 5, 2012

Why I don't like vocational education

Education should improve people. Training to do particular things can be a part of that, but it isn't the whole thing. Vocational schools say, in effect: "You are a lost cause. We can't help you get any better as a person, but maybe we can train you to work a particular job at a business that may or may not exist by the time you graduate." Vocational schools represent an abdication of responsibility, an abandonment of education's central commitment to humanity. They reduce their students to machines. Schools can certainly have vocational components - but a vocational school barely deserves to be called a school at all.

Monday, June 4, 2012

Expected value is not useful for making decisions about lottery tickets

It was a surprise to me when I learned that sometimes lottery tickets actually have positive expected values. This happens only rarely, and generally only for progressive jackpots. But I was alarmed that it happens at all. So often in the literature people are judged as irrational if they don't act in accordance with expected value. Should I buy a lottery ticket with a positive expected value?

For example, say someone offers you the following bet: we flip a coin, and if it comes up heads you get $10. If it comes up tails you lose $1. This game has expected value of +$10/2 + -$1/2 = +$4.50. Should you play this game?

If I can play this game arbitrarily many times, and I have a handful of dollars to start out with, I will play this game as a full time job, and I will be rich. After playing just six times the odds of losing money overall are under 1%, and that number goes even further to zero the more I play. I am quickly in a world where it is more likely that I am better off than I was before.

However, invite me to play this game just once, and I am ambivalent. Maybe I'll make some money, but it is equally likely that I will lose money. I don't think it is irrational to decline the offer to play just once. (Some might say that it is irrational because it should become one of many positive expected value opportunities that I take, ensuring a positive outcome overall, but (a) positive expected value gambling opportunities are notoriously rare, and (b) the typical slimness of the odds matters, as follows.)

Even the best positive expectation lottery ticket has odds much worse than one in a million, so let's take that as the odds for a $1 ticket. Say the prize for this bet is $2 million. The a ticket has an expected value of nearly +$1. (For simplicity in the following, I treat each lottery ticket as independent, which is not quite true, but is not such an awful simplification since in reality you can't buy enough lottery tickets to benefit significantly by owning a large portion.)

In the coin flip bet above, if you play twice you have over a 50% chance of having more money than you started with. How many times do you have to play this excellent one-in-a-million lottery game to be more likely to have won money than lost? log(0.5)/log(1 - 1/1,000,000) = nearly 700,000 times.

Both the coin flip and lottery here have positive expected value, and if you could play them arbitrarily many times, both would be cash cows. In the case of the coin flip, the generous single-game odds make it fairly easy to ensure that your odds of winning overall are excellent. But as the odds get worse, as in the case of the one-in-a-million bet, (still not bad, by lottery standards) the nature of the physical universe makes it nearly impossible to play enough games to achieve decent odds of a positive outcome.

I think it is rational to consider the probability of the overall outcome of gambling rather than the expected value of the gamble. It is not just about psychological "risk aversion" and it is not just about ignorance of expected value.

I have never seen an army of hedge fund quants scrambling for the nearest 7-11 to invest heavily in high-jackpot Powerball tickets. In any event, I won't be buying any - regardless of expected value.

Saturday, June 2, 2012

Thoughts and selections from The human side of school change

The human side of school change: Reform, resistance, and the real-life problems of innovations
Robert Evans


Here is a consultant who knew in 1996 that he needed to start saying "innovation" a lot. So now he's the keynote speaker at the upcoming NYC principals' conference, and all the principals are getting a copy of his book.

There is a lot to like about the book. The typesetting is gorgeous, for one. I wish it said what the font face is. But the author really does seem to be very intelligent, and the logical organization of the book is pretty good. It does irk me a bit how he seems to misuse "axiom" and to cite sources for claims that appear to be purely opinion. Overall: it's a book. There are some interesting bits:


One thing that I find interesting is how similar advice for principals managing teachers is to advice for teachers managing students:

"The extensive history of school reform has offered researchers ample opportunity to study the training that supports innovation. The findings are straightforward: to help teachers develop new competence, training must be coherent, personal, and continuous. Coherent refers to the design and sequencing of the training content. Sessions must be relevant to the innovation and unfold in a logical way that provides teachers with both an overview of the larger goals and a walk-through of the specific objectives and the methods for achieving them. Personal refers to the importance of tailoring training to the current knowledge, practice, and felt needs of teachers. ... New practices depend crucially on the amount of personal assistance teachers receive and how user-friendly this assistance is." (p. 63-64)

The continuous bit is about not expecting training once at the beginning to be sufficient forever onward. This is all good stuff, but hardly different than what works for teaching students. This comparison across organizational levels is an interesting perspective only occasionally encouraged in the text.


"Schlechty (1990, pp. 7, 17-28) identifies three competing conceptions of the purpose of schools that have influenced restructuring: as a tribal center (to transmit cultural enlightenment and traditions and norms of citizenship), as a factory (to select and sort students for future occupations according to standardized measures of performance), and as a hospital (to redress the pain and suffering imposed on children by society and to equalize opportunity)." (p. 89)


"(One of the most draining aspects of change for a leader is the seemingly endless need to correct misimpressions, to answer the same questions yet again, long after she had thought everyone understood.)" (p. 77)


'With regard to heterogeneity, despite academic research that tends to support its advantages for most students, moral arguments made for it on grounds of equity and social responsibility, and periodic reports from schools of remarkable successes, teachers continue to oppose it overwhelmingly. For one thing, heterogeneous classes are harder to teach than homogeneous classes of equal size. Since few districts cut class size when they change grouping patterns, heterogeneity makes teachers' lives more difficult. Moreover, the range of heterogeneity is expanding as the student population becomes more diverse and as inclusion introduces into classrooms greater numbers of special needs students with major learning and behavioral problems. I vividly recall a biology teacher in an urban high school describing what restructuring meant to him: "Over the summer, our high school was detracked. Just like that. In each of my five classes, I still have thirty-three kids, but they now speak eight different languages, their reading levels go from the 97th percentile down to the third, and there are at least four or five - in every class, mind you - with serious behavior or emotional problems. I'm almost totally reduced to multiple-choice worksheets. Some days I'm furious; others I'm depressed."' (p. 82)


It's a little interesting the way the author seems to sometimes refer to students as clients.


"Implementation happens during the school year and after the school day - there is no closing the factory to retrain the workers." (p. 85)

More and more, I think teachers should work all year. Even if students still get a summer vacation, teachers could develop curricula and so on during the summer. I remember how shocked I was after getting my first teaching job, at a public high school. "Do we have any sort of planning, workshops, or anything like that during the summer?" "Nope, just show up the day before classes start." That's no way to run a school.


"Restructuring exaggerates the causal role and curative reach of the school." (p. 86)

Probably true, not necessarily helpful.


This bumper sticker is quoted: "I Feel Better Now That I've Given Up Hope" (p. 95)


"It is an axiom of career theory that occupational satisfaction and achievement require require congruence between the characteristics of the individual and those of the work environment."

I tend to agree that that congruence is important, but I also think the author is here abusing the term "axiom" and exaggerating the degree to which "career theory" is the kind of thing that has axioms anyway.


"Schools have always depended for their success on a high degree of exploitation - getting maximum effort for minimum compensation - and it is far easier to exploit eager, innocent, unencumbered beginners than weary, wily, overloaded veterans!" (p. 117-118)


After listing these pressures of teaching: social complexity, multiplicity (which we might call multi-tasking), personal involvement, motivational burden, public nature, unpredictability, and professional isolation: "Every profession, of course, has its own pressures, but these characteristics make teaching an unusually draining activity, one marked by a sharp disparity between giving and getting." (p. 121)


"The deprivation they experience, coupled with many of the life and career changes noted in Chapter Six, incline teachers more strongly toward what is sometimes called a "union mentality" - that is, a militant antimanagement posture, a to-the-minute definition of the work day, and a reflexive, legalistic opposition to virtually any innovation that might impinge on contractual agreements. This may not be an inevitable response to a sense of being taken advantage of, but it is, in my view, a natural one. Employees who have long felt underpaid and who then see their social status slipping even as demands upon them increase are more likely to adopt an agressive, us-versus-them posture. The irony is that while this can increase teachers' muscle, it further diminishes their status. When it leads them to oppose changes in working conditions necessitated by certain reforms (say, a reduction in individual preparation periods to create more common planning time or a change in certification requirements to permit more interdisciplinary courses), it gives ammunition to their critics and leads the general public to see them as not only unprofessional but opposed to improvement." (p. 124-125) (emphasis mine)


"... replacing a traditional credit-hours graduation requirement with a formal exhibition of competence" (p. 126)

I just think this is a neat idea.


"... the year the Russians launched Sputnik, the first space rocket, terrifying America ..." (p.131)

I have difficulty taking an author seriously who describes Sputnik as "the first space rocket."


On page 136 the consultant author includes consulting as one of three major costs facing schools that want to succeed in restructuring. This guy is a consultant.


(quoting Bennis and Nanus, p. 21) "Managers, it is said, do things right, while leaders do the right thing." (p. 148)


(quoting Kouzes and Posner, p. 27) 'In this regard, the distinction between management and leadership is that managers "get other people to do, but leaders get others people to want to do."' (p. 172)


(quoting Kouzes and Posner, p. 43-44) 'Rather than "What gets rewarded gets done," we should apply a new axiom, one that helps explain why people seek to excel: "What is rewarding gets done."' (p. 172)

I don't know who it is for sure here, but somebody has problems with what "axiom" actually means. I like the idea though.


'The primary leadership strategy here is "what is good gets done."' (p. 173)


I do like the author's focus on good leaders acting in consistence with their values and otherwise being "authentic."


'An excellent example is Carl Glickman's call for schools to adopt a single overarching goal: to prepare students to be productive citizens of a democracy. Besting other nations in math or science, teaching basic skills or critical thinking - these are "subgoals of the larger, single goal of public education. When these subgoals are treated as primary goals, they lead to fragmentation, vulnerability, and despair as schools try to be all things to all people" (1993, p. 8).' (p. 228)

I like this a lot.


"What does focus mean in practice? It means something as elementary as it is rare: pursuing one major change at a time per person and per work group." (p. 217)


'Teachers' relations with one another are mostly marked by congeniality (being pleasant) but not collegiality (serious professional interaction). Though collegiality's benefits are "obvious, logical, and compelling," it is "the least common form of relationship among adults in schools," observes Barth (1989, pp. 229-230). ... The entrenched norms that prevail among teachers remain those of autonomy and privacy, "not open exchange, cooperation, and growth" (Johnson, 1990, p. 179).' (p. 233-234)


"Whatever they promise, shared governance and collaboration always mean more work - and more complex work, and more work with other adults rather than with students. They require greater investment in the workplace and higher levels of sophisticated adult interaction. Many teachers welcome neither." (p. 234)


"There is also the truth that many teachers, regardless of age, prefer to work with children than with adults. ... Even faculty who are gifted with students can be unhappy and awkward with adults. Two of the best teachers my children ever had were fabulous to watch in a classroom but incapable of looking a parent in the eye during a conference." (p. 234-235)


'This means that technical communication among teachers is more difficult, less necessary, in some ways even less appropriate than it might seem. It is moe difficult because two people can teach the same curriculum to similar students but operate in vastly different ways on vastly different assumptions that are hard to explain, let alone bridge. It is less necessary because in the most basic practical terms, schools can easily function as a set of independent workshops (quite unlike hospitals, for example, which literally cannot operate without close linkage among staff). And it is less appropriate because the separateness and "professional egalitarianism" that incline teachers to keep to themselves is routine among artisans. "Noninterference with the core work of others constitutes a sign of professional respect," while asking for assistance can seem a sign of weakness and offering unsolicited help a sign of arrogance.' (p. 235)


"From a school perspective, the competitive corporate ethos can seem cruelly hard. From a business perspective, the school ethos seems childishly soft." (p. 275)


"But changing education, Elmore and McLaughlin suggest, is rather like changing a language: formal efforts to modify usage don't usually succeed at first and rarely turn out exactly as they were intended, but over time a language makes dramatic changes, incorporating a variety of new influences in diffuse and uneven ways." (p. 294)


'Without a basic "values consensus" about the purpose of education, substantial improvement in school performance is unlikely (Schlechty, 1990, p. 28). This is not a call for national curriculum standards but for a better purposing at a fundamental level.' (p. 296)