Going into space? If you can’t wear a blue shirt then make sure you have a red one.
Significance magazine has analysed the casualties in Star Trek:TOS. Everyone knows that wearing a red shirt on the USS Enterprise is like wearing a giant shoot me sign. But what everyone knows might be wrong.
Matthew Barsalou has analysed the casualities and found blue is the safest colour. He’s also found more red shirts died than any other colour — but on the Enterprise there are more red shirts anyway. The situation is made more complicated by security, engineering and operations all wearing red shirts even though they do very different jobs.
If you’re a space cadet this is essential reading.
Reshared post from +K. Llewellin
Keep your redshirt on: a Bayesian exploration — Web Exclusive Article — Significance Magazine
Keep your redshirt on: a Bayesian exploration. Author: Matthew Barsalou. The idea of red-shirted characters being frequently killed in Star Trek: The Original Series has become a pop culture cliché. B…
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This very briefly introduces the statistical method I used to analyse the Greek temples of Sicily for astronomical alignments. It’ll be the basis for a paper On the Orientations of Greek Temples in Sicily. The whole thesis will be made available later via Open Access some way or another. I would say via the British Library’s EThOS system, but I’ve had no luck with that.
I’m falling behind on my reading of RSS feeds, so the news that the Portable Antiquities Scheme has put some of its data on Swivel is new to me, even though the post is a week old. Swivel seems to be a graphing website. People upload data and then you can draw your own graphs from it.
At the moment some of the graphs are a bit limiting. There’s not a lot you can do with the number of coins by period for example. I think it does show potential for the longer term. For instance with the PAS database being open it should be possible to mash it with other data and produce some really useful or bizarre results. For instance is archaeology a middle class pursuit? The PAS has some findspot data, so you could plot number of finds in a county against number of trendy wine bars in a county and see if there’s a correlation. You can’t do that with Swivel yet, but it looks like it might be possible in a few years time. Perhaps a more useful study would plot PAS find numbers in with a series of socio-economic indicators like crime reports, schools performance etc which might help heritage workers see where they are succeeding and where they are not.
Despite that, even though I think it’s exciting I still don’t know what I’m getting excited about. I remember the first mobile phones coming out in the eighties. Who would have predicted then that the big selling point about them would have been cameras or text? Who then predicted what personal communication would mean for the decline in public phones? The way we think about electronic communication today is qualitatively different to the way we thought about it in the past. I think this kind of openness with data could produce something similar. At the moment I’m still thinking about data in a conventional way. I suspect that will its availability people only a little more visionary than me will come up with new ways in thinking about information, and take that view for granted like we take cameraphones for granted today.
In the longer term I could be worried about these young upstarts who’ll be thinking in a different way and make me something of a dinosaur. In the shorter term I’ll seriously consider putting my data online at Swivel after I’ve finished my thesis and contribute to the process.
Carl Feagans mentions the Tomb of Jesus brouhaha. I plan to put up something on this, but I’m holding back for now as I’m waiting for a couple of email replies. I’ve sent one to Professor who produced the 600:1 claim. I’ve tried seeing the press conference to see how he gets that figure, but it’s not working for me. The way they present the data in the document pack suggests if you’re not expecting Jesus to be married to Mary Magdelene then the probability falls from 600:1 to around 4:1.
The problem is that the statistical analysis is presented as being so ham-fisted that I have to assume something is missing. For instance I can’t work out how Historical Bias = 4. This is only a summary so I’m only 64.56732% sure this is a spurious figure plucked from the air. There could be harder archaeological reasons for saying why this figure is justified from an analysis of more ossuaries. Alas, the pack given by Discovery, despite their claims doesn’t give you the evidence to judge for yourself.
You can download the pack without working your way through all the Flash navigation and read a couple of articles, a couple of maps and the calculations for yourself. Mapwise it seems fairly conclusive that the tomb was buried. Article-wise one is reading the inscriptions and the other is on the context of the Ossuaries by Prof. Amos Kloner, who doesn’t support the attribution of the tomb.
A follow-up to The Orientation of Roman Camps and Forts. This is an application of the Binomial Distribution test that I’m using in my own work applied to the data from the original paper, which is why you may have the impression you’ve already read this recently. My analysis may not be correct, so I’m putting it up on iScience and submitting that to Carnival of Mathematics and Tangled Bank to see if people think the maths is wrong. I’m also putting it up on Revise and Dissent where it will get submitted to the History Carnival and Four Stone Hearth to see if it’s intelligible and sounds reasonable to Historians and Archaeologists.
Roman Camps and their Orientations reconsidered.
There is currently a debate in the pages of the Oxford Journal of Archaeology on the orientations of Roman camps and forts. Richardson (2005:514–426) argues that the orientation of these camps is non-random and relied on some form of astronomical observation. He presents data which he argues supports his case. Recently Peterson (2007:103–108) has argued this relies on a flawed use of the Chi-squared test. I accept Peterson’s findings that Chi-squared is not a useful method. However examining the camps as a binomial distribution would be feasible and would make explicit the archaeological and astronomical assumptions made in the argument.
What is a Roman Camp?
The sites being examined are Roman camps and forts in England. One of the major advantages that the Roman army had over the native opposition when occupying new territory was their organisation. The Roman army was effectively a professional army taking on amateurs. Their camps reflect this organisation. Typically their early camps a ditch surrounded by a bank in a playing-card shape. They followed a set design. The rationale for this was if there were attacked by surprise equipment and people would be in the same place at each camp, minimising the effects of the surprise.
The ancient sources give some detail on how to lay out a Roman camp. The main gate should face the enemy, or the line of advance (Vegetius 1.23, Hyginus 56). The rear gate should be on the higher ground to aid surveillance. Sites overlooked by hills were considered a bad idea, as were sites near woodlands which would allow the enemy to sneak up on the camp. The basic layout of the camp could be set up quickly by surveyors using gromae, surveying tools for laying out lines at right angles. Hyginus (chapter 12) states that you set up your groma at the junction at the centre of the camp and lay out your roads to the gates from there.
This would appear to be an efficient method of laying out a camp. Were observations to orientate the camp also part of the method? It doesn’t seem necessary, but Richardson (415,422–23) provides quotes from ancient sources which suggest this is plausible hypothesis in some circumstances.
In a previous post I looked at whether or not Greek temples faced East. The definition I used of East was very broad, the eastern half of the sky. No-one, as far as I know, has suggested that this was sufficient for the Greeks. Penrose, writing in the late nineteenth century and Dinsmoor in the mid twentieth century both thought that the temple could face sunrise on the feast day of the god of the temple.
This sunrise will not always be due East. Because of the tilt of the Earth’s axis and the motion around the sun this sunrise will vary in location on the horizon. In my thesis this will be dealt with at an early stage. If you want a graphic illustration then there’s this nice animation you can play with at the Nebraska Astronomy Applet Project.
Below continues from the earlier post.
To test the applicability of this method further I shall now consider a marginally different hypothesis, that Greek temples faced sunrise. This is different to facing the eastern half of the sky as the sun only rises and sets within a specific range. For the latitude of Sicily, assuming the local horizon is flat, this range would be between 59° and 119°. This is a range 58° wide, approximately one-sixth of the horizon. Within this range thirty-eight of the forty-two temples face within this range. This would be rather like throwing a typical die forty-two times and throwing a six thirty-eight times. This is highly unlikely to be due to chance. Typically on average in any set of forty-two randomly aligned temples, seven would be expected to face within the range due to chance. The standard deviation would be approximately 2.42. Therefore 95% of sets would have between four and ten temples facing within this range. This therefore appears to be significant but raises the question of how this feature is to be explained.
So this is what I’ve been working on this week. I’ve been looking at the orientations of Greek temples. There is an idea that Greek temples always face east, and that’s what I’m testing at the moment. If I can show that Greek temples do face East then things get interesting. This is because in Sicily in the first millennium BC the natives take on a lot of Greek material. If I can show that the natives are still practising their own religions in their own way, then I have strong argument that they’re using Greek pottery and so on for their own purposes rather than simply becoming Greeks themselves. I have results and I’m trying to put them together meaningfully.
A lot of the significance depends on the data set and how I use it. For instance if I have only one temple and it points East, that doesn’t really mean a lot. It has to point somewhere, so why should that be special? It could face that way by chance. If I have two temples facing East then that’s a bit better, but it’s still hardly impressive. At it happens I have measurements for forty-two temples, but not all of them face East. So are my results significant? Below is me trying to work this out and come up with a better answer than: “Yes, because I say so.” It follows quite a few other chapters in the thesis, so it might not all make sense, but it should make enough sense for people to point out any obvious mistakes in my handling of probability.
Some of the formulae may seem a little odd, but hopefully they’re clear enough. I’ll have to get to grips with MathML to generate some formulae graphics for the actual print. This is very much first draft material.
I thought it might be useful to define what I mean when I use words like ‘probable’ or ‘possible’, so I’ve created my own scale to define how likely I think something is to be significant. It’s meant for whether or not an astronomical correlation is meaningful to archaeological material, but it probably has general applications.