Wednesday, July 27, 2011

A laundry list of observations about blogs

The following have been building up over some time.

  • If you read blogs but wouldn’t want to write one, you may still want to consider making a “passive” blog that contains the ones you read, since it’s great to automatically get a list of them ranked by how recently they were last posted to.

  • If you want to kill yourself and make it look like you are still alive, simply write up a few blog posts and use the “post options” to cause them to be published at whatever times you like in the future, that way you continue to blog from beyond the grave.

  • The great thing about blogs, in contrast with Facebook, Google+ etc is the simplicity of the contract between writer and reader: anyone can read your stuff without having to sign up in any sense. There are no nasty surprises in privacy settings. It’s true that Google+ allows you to declare some of your ramblings to be public, but that’s not the same somehow.

  • Putting together a blog post is quite a satisfying work of craftmanship1; I couldn’t get the same feel from using Twitter, although I see there may be an interesting challenge to packing some observation into 140 characters.

  • Studying one’s pageview statistics can get rather addictive if you’re not careful. Blogger lets you pull up very detailed charts showing pageview history, which web sites, countries etc produced the pageviews, etc.

  • When I set up my Google+ account, it integrated in my picasaweb photos, which turns out to mean the pictures that I have in the past used to illustrate blog posts. Along with other stuff I had forgotten about (like some stuff on Google docs), all of which I found a bit spooky.

1this post being something of an exception

Sunday, July 24, 2011

Conferences becoming like journals?

A recent post (on spotting bugs in papers) at Claire Mathieu's blog reminded me of something a colleague told me recently: he noted that conferences are requiring more mathematical rigour from submitted papers, than they used to (say, about 10 years ago). Where previously we could get away with “proof (sketch)” there is now a stronger expectation that the whole thing will be written down, either in an appendix or on Arxiv. If we make a mistake we now face rejection; no longer do we just try to convey the general idea, but it’s required that the details be done correctly. My own limited experience agrees with the theory that this is a trend, but I am mainly just passing on hearsay. (Let me know if you think this is indeed a trend.)

This all seems fine, and yet... I have concerns. The main one is the risk that conferences threaten to usurp the traditional role of journals, in purporting to showcase papers that are guaranteed to be correct. The traditional life cycle of a paper envisages a conference version that publicizes the idea, which results in the author(s) receiving feedback on the paper, that may inform or contribute to a subsequent journal version, whose main purpose is to be correct, in some cases setting the record straight if there are bugs in the conference version. If we’re going to insist on correct conference papers, it raises the question of whether the guarantee is as strong as it is for journal versions. If so, there is no point in the journal paper.

Should we mind if a few conference papers are buggy? I’m not sure that’s such a big problem. If the paper attracts interest it will receive sufficient scrutiny to detect errors, and furthermore will be submitted for journal publication (as warranted by the interest it attracts). Thus, a buggy paper will either get exposed, or else no-one will read it. Moreover, is it even desirable that our literature should be entirely pure — is there not room for the human factor to obtrude? There is mild entertainment to be obtained from the occasional reminder that a paper may have been driven by over-enthusiasm on the part of its authors, and it can be reassuring to see that even our more esteemed colleagues sometimes get things wrong.

Thursday, July 14, 2011

Higher education white paper

Wikipedia tells us that a white paper is “an authoritative report or guide that helps solve a problem”. Some of us might say that Students at the Heart of the System poses a challenge to that definition. I don’t have time to read it, but I did take a look since the various article in the press are not very informative. There’s an executive summary of sorts here, but it’s a bit one-sided.

At the beginning of the white paper, we read:
Higher Education is a devolved matter in Scotland, Wales and Northern Ireland so this is a White Paper for England. [...] All facts, figures, policies and actions refer to England only, except where stated otherwise. “National” should be taken to mean England-wide except where the context indicates otherwise.
(I feel a twinge at this. Maybe we should not care about national identity, but when it comes to Higher Education, England always gets the thin end of the wedge.)

My interest was in the way student numbers are to be managed. The discussion of this topic was done with reference to the current system under which universities get quotas of students. The quota system is portrayed by its critics as providing universities with a captive customer base, relieving them of the need to compete, and disallowing any kind of market to guide student recruitment. That is not quite fair; back when I was at Warwick, for a while Computer Science was getting far more prospective students than we could take, and we (the university) applied to HEFCE and got the quota increased. But, admittedly it was slow, and I think it was a collective university quota that was raised; it was left to the university to expand the department and I have no idea how much attention HEFCE paid to that process. Naively, if you’re in a system where “the funds follow the students” it looks like popular institutions would be able to expand to meet demand, and unpopular ones would contract, all of their own accord.

If I’ve got the right general idea, that principle is to be applied to students who get AAB or better at A level (see paragraph 4.19 of the paper. There are about 65,000 such students (out of a total national annual cohort of about 480,000). Student quotas get scaled down to cover the remaining 415,000 places, and presumably if your fraction of AAB students is below average, you lose out, and if it’s above average you could expand. But there are plenty of unanswered questions, and paragraph 4.12 notes that “the sector” is being consulted on the details. (So, some of the vagueness in reports on this document stem from lack of conclusions it has, in some respects.)

Some forecasts: much wrangling about who should count as a high-achieving student: AAB at A level does not address the “widening access” agenda: students with non-traditional qualifications lose out. Since some A levels are considered better than others, there will be discussion about whether A level grades should be deemed to be the same, or not. A potential boost for General Studies if they’re all deemed the same. With regard to a further 20,000 places to be assigned to institutions that charge less than £7,500 on average, after various discounts: an unexpectedly high number of institutions could claim eligibility for those. That is because the rush to charge £9,000 was partly based on the understanding that the effective fee will always be less, together with the fact that £7,500 is needed to break even. So, places that announce £9,000 may often just be expecting to get £7,500.

This article in the Times Higher provides a robust criticism of the white paper. Here’s a quote:
The intention to place teaching on a par with research is laudable, but this cosmetic fix short-changes everyone. A document that has been touted as putting students in the "driving seat" sounds good in theory, but there is a reason why young drivers pay high insurance premiums: they have a high risk of coming unstuck because they lack experience of the road ahead.
A contrasting article at the Adam Smith institute blog points out that Adam Smith went to study at Oxford and was dismayed that the professors were not being incentivized to teach. He approved of the system at Glasgow, under which he taught, and was paid, in some sense, directly by the students. But this seems to be an argument against “putting students in the driving seat” — if Adam Smith got it wrong, why should today’s students do any better?

Monday, July 11, 2011

Prepayments on student tuition fees

There is pleasure (but not much) to be had from the spectacle of a Government department caught up in a web of its own contradictions. The Dept of Business, Innovation and Skills (BIS) is currently consulting on whether there should be a scheme for early repayment of tuition fees, and what should the rules be.

Recall that the current plan is that interest on student loans is to be charged at Retail Price Index plus 3%. BIS say:
We are committed to the progressive nature of the repayment mechanism. It is therefore important that those on the highest incomes after graduation are not able unfairly to buy themselves out of this progressive mechanism by paying off their loans early. That is why we are consulting on potential early repayment mechanisms – similar to those paid by people who pre-pay their mortgages.
This quote is an admission that the Government is rubbing its hands at the prospect of lots of lovely interest being paid on their loans, and don’t want to let people pay them off early. The word “progressive” has been hijacked to refer to a scheme for keeping us all in debt for as long as possible. (Should people who can buy houses without mortgages be prohibited from “unfairly” buying them without incurred interest payments?)

Digging deeper into the consultation document, we get:
These mechanisms would need to ensure that graduates on modest incomes who strive to pay off their loans early through regular payments are not penalised. For example, a five per cent levy might be charged on additional repayments each year over a specified amount such as £1,000 or £3,000. Alternatively, those on higher incomes (e.g. over £60,000) who made an additional repayment could be required to pay a five per cent levy on this sum.

Further down, they admit that there’s a case in favour of allowing early repayments, in that “It allows graduates on modest incomes to pay off their loans early.” Here they flat-out contradict themselves by admitting that people should actually be encouraged to pay their debts. Provided, that is, you’re on a “modest income” — if someone who could actually afford to repay tries to do so, well, that would just not be cricket.

I could go on, but there’s no need to; for anyone who wants to read further criticism there are some good responses on the web site; I recommend the comment by Tim Leunig.

Wednesday, July 06, 2011

hat tricks

Among many things the internet has been blamed for, is the phenomenon of people only ever reading stuff that they agree with, and thereby reinforcing their opinions without having them challenged. By analogy, do we spend too much time hanging out with our familiar research communities? At the 23rd British Combinatorial Conference, to which I was invited to give a talk, I now have to struggle to come to terms with research on topics that have obvious computational questions, but where it’s other questions that get considered.

One talk was on a topic that is, at a stretch, vaguely game-theoretic: “Hat problem on a graph” by Marcin Krzywkowski relates to a kind of puzzle described here1, in particular the 3 hat problem. Three players are fitted with hats, each hat may be either red or blue, the colour chosen uniformly at random. Of course, you can see the other players’ hats but not your own. Each player may (simultaneously) make a guess as to his own hat colour, or else abstain from guessing. They win if at least one player makes a correct guess and no player makes an incorrect guess. For this 3-player case there is a simple guessing scheme whereby their win probability is 3/4. As hinted in this version of the puzzle, if the players can flip coins, there is a randomized scheme that lets them win with probability 3/4 even if the hats are allocated by an adversary — but the adversary should not be able to eavesdrop on their coin-flipping before they get fitted with the hats. (A question: suppose the adversary can eavesdrop on them beforehand but then they can flip coins after the hats have been fitted. The players can win with probability 1/2 by delegating one of them to guess at random. I don’t think they can do better and would guess there should be a nice proof that even works for any number of players, but haven’t figured one out.)

Back to the paper — suppose there are n players and suppose that there are some restrictions on which players can see each others’ hats. It is natural to represent this with a graph on the players, in which a player can see only his neighbours, so that the basic hat problem would assume the complete graph. Then, one can ask how well the players can do for various kinds of graph. If I recall correctly, the players can win with probability 1/2 if the graph is a path; other kinds of graph are also considered.

1I thank Sophie Huczynska for drawing my attention to this web site.