Archive for Oxford University

Value Added?

Posted in Bad Statistics, Education with tags , , , , , on October 22, 2012 by telescoper

Busy busy busy. Only a few minutes for a lunchtime post today. I’ve a feeling I’m going to be writing that rather a lot over the next few weeks. Anyway, I thought I’d use the opportunity to enlist the help of the blogosphere to try to solve a problem for me.

Yesterday I drew attention to the Guardian University league tables for Physics (purely for the purposes of pointing out that excellent departments exist outside the Russell Group). One thing I’ve never understood about these legal tables is the column marked “value added”. Here is the (brief) explanation offered:

The value-added score compares students’ individual degree results with their entry qualifications, to show how effective the teaching is. It is given as a rating out of 10.

If you look at the scores you will find the top department, Oxford, has a score of 6 for “value added”;  in deference to my alma matter, I’ll note that Cambridge doesn’t appear in these tables.  Sussex scores 9 on value-added, while  Cardiff only scores 2. What seems peculiar is that the “typical UCAS scores” for students in these departments are 621, 409 and 420 respectively. To convert these into A-level scores, see here. These should represent the typical entry qualifications of students at the respective institutions.

The point is that Oxford only takes students with very high A-level grades, yet still manages to score a creditable 6/10 on “value added”.  Sussex and Cardiff have very similar scores for entry tariff, significantly lower than Oxford, but differ enormously in “value added” (9 versus 2).

The only interpretation of the latter two points that makes sense to me would be if Sussex turned out many more first-class degrees given its entry qualifications than Cardiff (since their tariff levels are similar, 409 versus 420). But this doesn’t seem to be the case;  the fraction of first-class degrees awarded by Cardiff Physics & Astronomy is broadly in line with the rest of the sector and certainly doesn’t differ by a factor of several compared to Sussex!

These aren’t the only anomalous cases. Elsewhere in the table you can find Exeter and Leeds, which have identical UCAS tariffs (435) but value added scores that differ by a wide margin (9 versus 4, respectively).

And if Oxford only accepts students with the highest A-level scores, how can it score higher on “value added” than a department like Cardiff which takes in many students with lower A-levels and turns at least some of them into first-class graduates? Shouldn’t the Oxford “value added” score be very low indeed, if any Oxford students at all fail to get first class degrees?

I think there’s a rabbit off. Can anyone explain the paradox to me?

Answers on a postcard please. Or, better, through the comments box.

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The Necessity of Atheism

Posted in History, Literature, The Universe and Stuff with tags , , , , , , , , on February 15, 2011 by telescoper

In the course of doing a crossword at the weekend, I learnt that the poet Percy Bysse Shelley was sent down from (i.e. kicked out of) Oxford University 200 years ago this month for writing a pamphlet entitled The Necessity of Atheism. He was at University College, in fact. A bit of googling around led me to the full text, which is well worth reading whatever your religious beliefs as it is a fascinating document. I’ll just quote a few excerpts here.

The main body of the tract begins There is No God, but this is followed by

This negation must be understood solely to affect a creative Deity. The hypothesis of a pervading Spirit co-eternal with the universe remains unshaken.

That’s pretty close to my own view, for what that’s worth.

More interestingly, Shelley goes on later in the work to talk about science and how it impacts upon belief. A couple of sections struck me particularly strongly, given my own scientific interests.

In one he tackles arguments for the existence of God based on Reason:

It is urged that man knows that whatever is must either have had a beginning, or have existed from all eternity, he also knows that whatever is not eternal must have had a cause. When this reasoning is applied to the universe, it is necessary to prove that it was created: until that is clearly demonstrated we may reasonably suppose that it has endured from all eternity. We must prove design before we can infer a designer. The only idea which we can form of causation is derivable from the constant conjunction of objects, and the consequent inference of one from the other. In a base where two propositions are diametrically opposite, the mind believes that which is least incomprehensible; — it is easier to suppose that the universe has existed from all eternity than to conceive a being beyond its limits capable of creating it: if the mind sinks beneath the weight of one, is it an alleviation to increase the intolerability of the burthen?

The other argument, which is founded on a Man’s knowledge of his own existence, stands thus. A man knows not only that he now is, but that once he was not; consequently there must have been a cause. But our idea of causation is alone derivable from the constant conjunction of objects and the consequent Inference of one from the other; and, reasoning experimentally, we can only infer from effects caused adequate to those effects. But there certainly is a generative power which is effected by certain instruments: we cannot prove that it is inherent in these instruments” nor is the contrary hypothesis capable of demonstration: we admit that the generative power is incomprehensible; but to suppose that the same effect is produced by an eternal, omniscient, omnipotent being leaves the cause in the same obscurity, but renders it more incomprehensible.

He thus reveals himself as an empiricist, a position he later amplifies with a curiously worded double-negative:

I confess that I am one of those who am unable to refuse my assent to the conclusion of those philosophers who assert that nothing exists but as it is perceived.

This is a philosophy I can’t agree with, but his use of words clearly suggests the young Shelley has been reading David Hume‘s analysis of causation.

Later he turns to the mystery of life and the sense of wonder it inspires.

Life and the world, or whatever we call that which we are and feel, is an astonishing thing. The mist of familiarity obscures from us the wonder of our being. We are struck with admiration at some of its transient modifications, but it is itself the great miracle. What are changes of empires, the wreck of dynasties, with the opinions which support them; what is the birth and the extinction of religious and of political systems, to life? What are the revolutions of the globe which we inhabit, and the operations of the elements of which it is composed, compared with life? What is the universe of stars, and suns, of which this inhabited earth is one, and their motions, and their destiny, compared with life? Life, the great miracle, we admire not because it is so miraculous. It is well that we are thus shielded by the familiarity of what is at once so certain and so unfathomable, from an astonishment which would otherwise absorb and overawe the functions of that which is its object.

Finally, I picked the following paragraph for its mention of astronomy:

If any artist, I do not say had executed, but had merely conceived in his mind the system of the sun, and the stars, and planets, they not existing, and had painted to us in words, or upon canvas, the spectacle now afforded by the nightly cope of heaven, and illustrated it by the wisdom of astronomy, great would be our admiration. Or had he imagined the scenery of this earth, the mountains, the seas, and the rivers; the grass, and the flowers, and the variety of the forms and masses of the leaves of the woods, and the colors which attend the setting and the rising sun, and the hues of the atmosphere, turbid or serene, these things not before existing, truly we should have been astonished, and it would not have been a vain boast to have said of such a man, Non merita nome di creatore, se non Iddio ed il Poeta. But how these things are looked on with little wonder, and to be conscious of them with intense delight is esteemed to be the distinguishing mark of a refined and extraordinary person. The multitude of men care not for them.

I think the multitude care just as little 200 years on.

P.S. The quotation is from the 16th Century Italian poet Torquato Tasso; in translation it reads “None deserve the name of Creator except God and the Poet”.


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Operation Skyphoto

Posted in The Universe and Stuff with tags , on December 9, 2008 by telescoper

Katherine Blundell from Oxford just contacted me with a request that I post the following message. I’m more than happy to oblige.

Dear All,

There is a one-off opportunity to buy vintage prints of the original photographic plates of the Palomar All-Sky Survey. Although no longer useful for science (they fell into disuse two decades ago because of modern data digitization) they make rather handsome objets d’art when suitably mounted and framed.

These prints are for sale to raise money for Alexander Thatte’s treatment for leukemia – Alexander is the 5-year old son of two of our colleagues.

The mounted/framed photographs could make very nice Christmas presents. For a small additional payment we can deliver them to you already tastefully gift-wrapped.

A very limited number of photographs have kindly been signed by Jocelyn Bell Burnell – please email us if you wish to request one of these.

Please see http://www.physics.ox.ac.uk/skyphoto for an order form and further details. Please feel free to forward this email to anyone whom you think might be interested in purchasing a piece of astronomical history, and helping a child in need.

Best wishes,

Katherine & the Astro Grads

I can’t think of a better Christmas gift for an astronomer.

Go on. You know you want to.

If you leave it too late to buy your presents you might end up buying something really naff. Like a paperweight.

Look, I’ve even made it easier for you. Just click the link here.

So now there’s no excuse. Do it. Buy one. Now.