Going into space? If you can’t wear a blue shirt then make sure you have a red…

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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

#startrek   #stat­ist­ics  

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…

Starlight Expressed

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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.

Portable Antiquities Data and Swivel

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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.

The Tomb of Jesus

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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.

Roman Camps and Orientations

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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.

Wallsend fort
A Roman fort at Wallsend. Photo from Google Earth

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.
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Do Greek temples in Sicily face the rising sun?

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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.
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The probability of a temple facing East

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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.
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