Posts tagged Statistics
Starlight Expressed
Aug 5th
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
Mar 8th
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 More >
The Tomb of Jesus
Feb 26th
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 More >
Roman Camps and Orientations
Feb 17th
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 More >
Do Greek temples in Sicily face the rising sun?
Feb 4th
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 More >
The probability of a temple facing East
Feb 3rd
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 More >
The Scale of Likelihood
Apr 15th
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. (more…)
