The lost tomb of Jesus (or the seductiveness of statistics)
I remember his anger and frustration more than anything else. They created rather a tense atmosphere among us all. His emotions were memorable simply because they seemed so out of character. He was an easy-going individual, and I had never seen him so annoyed.
I was sitting in a lecture-theatre, waiting for the next lecture in a Statistics course, when he began his tirade. This course was taught by the professor himself, a mild-mannered character. But something had, as they say, ‘got his dander up’. He spent the opening minutes berating those who abused his beloved subject, for their own nefarious ends.
You see, statistics is about collecting and analysing and interpreting data. Let me hold my hand up right away and explain that I disliked the subject and was not much good at it. That I studied it for my first two years at university was, for me, an exercise in endurance. But I did grasp the professor’s point – that statistics can be used unscrupulously. On this occasion, his anger had been aroused because one particular research project had reached what he regarded as ridiculous conclusions, by a misuse of statistics. The good professor went on to insist that, when we worked with any kind of data, we must be clear at the outset what assumptions we were making as we analysed that data. Often our assumptions were guiding our conclusions more than the data, and we needed to learn how to spot this. In particular, where had the data come from? Was it reliable? Was it representative? What were we assuming about that data? And so he went on. Very often it was not the application of the statistical techniques which was flawed, but the assumptions made about the original data.
I was reminded of the good professor as I read about James Cameron’s much publicised documentary claiming to have found the tomb of Jesus. You see the claim rests, believe it or not, on a rather dubious use of statistics. I have a strong suspicion that James Cameron’s documentary might make its way into the annals of ‘how not to use statistics.’
10 ossuaries, dating from the first century were found in the Talpiot suburb of Jerusalem in 1980, by building workers. 27 years later James Cameron and co. have made a controversial documentary, claiming the tomb to be that of Jesus.
The caskets contain the names Jesus, Matthew, two versions of Mary and that of Joseph. It is further claimed that the bones and tomb date from the time of Jesus, and so the crucial question is – what is the likelihood that another family at the time would have the same names? This is where the statistics come in. Andrey Feuerverger, the Toronto Statistician involved in the documentary, arrived at the odds of 600 to 1 against. These odds then substantiate the conclusion that this tomb must therefore be the tomb of Jesus. Since the Christian Faith rests on the Resurrection of Jesus, the idea that his bones are lying in a tomb somewhere caused no little fuss.
So where did these odds come from? Feuerverger decided to try to work out what names were in use at the time of Jesus in order to work out the chances of those particular names being found together in one family. He claims to have used a source called ‘The Lexicon of Jewish names in late Antiquity’ to ascertain the odds. That very work makes it clear that the names found in the tomb were very common. One in three Jewish women were called Mary, one in twenty Jewish men called Yeshua (Jesus). Indeed, the author of the Lexicon (Tal Ilan) insists that there are numerous tombs where these very names are found and that the discovery of these names is simply a result of the names being common. He vigorously disputes the conclusions being made in the documentary.
To substantiate his high odds, Feuerverger insists that one of the the names for Mary, found in the tomb, is so unusual that, instead of being found in 1 in 3 caskets, as the lexicon would suggest, the odds should be 1 in 80. This assumption helps his case that this is an unusual list of names, by inflating the probability numbers. In fairness to him, he concedes:
"I did permit the number 1 in 600 to be used in the film—I'm prepared to stand behind that but on the understanding that these numbers were calculated based on assumptions that I was asked to use," says Feuerverger. "These assumptions don't seem unreasonable to me, but I have to remember that I'm not a biblical scholar."
Colin Aitken, a professor of forensic statistics at Edinburgh University, stated, "even if we accept the assumptions, 600 to 1 is certainly not the odds in favour of this tomb being Jesus.". In other words, even if it were true that to find this cluster of names is very unlikely, it does not follow that therefore this is probably the tomb of the family of Jesus. All you have calculated is the probability of finding a group of names together. Feuerverger has already backtracked from his claims, explaining on his personal website: "I now believe that I should not assert any conclusions connecting this tomb with any hypothetical one of the NT family."
The point is that this is largely a debate, not about tombs and bones, but about statistics and the credibility of the assumptions being made. Many, who have no particular religious stake in the whole business, have challenged the assumptions made by the documentary makers.
Of course, this all sets to one side the evidence that Christians bring in support of the resurrection of Christ – the gospel records, the secular testimony about the disappearance of Jesus’ body, the dramatic change which took place among the early believers, from being crushed and demoralised individuals after the crucifixion, to being a dynamic group who were accused of turning the word upside down in their quest to convince others of the risen Christ.
Out of interest, I found a website which gave me the statistics of popularity of names and I worked out the probability of a randomly chosen individual bearing my name (Martin) and the names of the rest of my family (Lorna, Philip, Jonathan, Lewis). I then worked out the probability of a family of five having these five names together. It works out that the chances of a family such as ours existing with such names is less than 3 in 1,000,000,000,000,000.
Which tells me nothing much, except that 1 in 600 isn’t such long odds after all. But it probably tells James Cameron that the Manse family in Dalry doesn’t exist.
Your minister and friend