The Bayes theorem applied to the Scandal

The Bayes theorem applied to the Scandal

A friend sends along the following analysis:

Early indicators are that 5% of Catholic clergy in the US since 1950 have been implicated in sex abuse of a minor.

These indicators also show that roughly 90% of these incidents of abuse are homosexual in form, with about 80% involving male post-pubescent youth, and the remainder pre-pubescent boys.

Let’s assume that Richard’s Sipe’s estimate of homosexually active priests is correct, at 15% of all clergy. (Although some have estimated the numbers as high as 40 percent, I think that’s too high. Fifteen percent is conservative.)

Then, according to the Bayes Theorem*, the probability of abuse being perpetrated upon a child by a gay priest is 30%, a pretty high proportion, but still under 50%! (This doesn’t analyze the probability of whether a priest will be faithful to celibacy promise at all, including with adults.)

Also, the probability of abuse being perpetrated by a ‘straight’ priest is 0.6%, a value somewhat less than that of the gays.

…..let’s see, that’s an Odds Ratio of 51 to 1, or, the gay is a mere 51 times more likely to hit on a minor than the straight.

Who was it… oh yes, it was Father Stephen Rossetti of the St. Luke’s Institute, who said that gays are no more likely to abuse a minor than straights.

I wonder if the insurance actuaries base their calculations on the views of the Rev. Rossetti or formula of the Rev. Bayes?

(note: Rev. Thomas Bayes (d. 1761) was a Presbyterian minister.)

Update For clarification and simplifaction, let me re-phrase the conclusion. The likelihood that an abuser will come from among the population of homosexual priests is 51 times higher than it is he will come from among heterosexual priests, because a smaller population (as a percentage) is reponsible for the vast majority (90 percent) of abuse cases. So, it’s not just 9 times greater, but 51 times greater.

Written by
Domenico Bettinelli
  • Sipe may be a liberal and dissenter and unreliable on some things, but it doesn’t make him wrong on this. Most observers, conservative and liberal, agree that his estimates of the number of homosexuals in the priesthood are accurate or even a little low. His numbers can be right if his subsequent conclusions about what they mean are wrong.

  • Courage,

    I’m not sure I understand. The numbers are based of numbers of abusers (no. of abusers compared to the total number of priests), not incidents per abuser. It wouldn’t lower the ratio, it would be a different ratio. And it wouldn’t change the probability of a homosexual priest being an abuser versus a heterosexual.

  • Okay, but I don’t understand how it invalidates the analysis. If homosexual priests, on average, abuse more victims, then the probability that one would be abused by a homosexual priest would still seem to be higher by a ratio of 51 to 1 because they cast a wider net.

  • The “probability” that a homosexual priest will have committed any one incident of abuse is 51 times higher than the “probability” that a heterosexual priest will. It takes into account both the percentage of homosexuals in the priesthood along with their higher average number of victims.

    Look, I don’t know statistics, but the guy who sent it to me does. Maybe somebody who knows math and stats could chime in.

  • I use statistical formulae in my work everyday so don’t be in awe of the math.  The data demonstrates that there’s a homosexual problem in the priesthood.  A priest is (or at least was) given authority over and access to children and adolescents that a non-priest doesn’t have, as well as the trust of parents and the larger community.

    Whether it is a irresistable temptation or a deliberate strategy, the number of incidents involving homosexuals priests shows that the Church hierarchy has to name the affliction: homosexuality—and not pretend this is an issue that has nothing to do with it.  Confront the truth.

  • The 90 percent figure is not an assumption. It is the conclusion of the John Jay report about to be released based on the compilation of all data. As for the percentage of priests that are homosexual, there may not be hard numbers, but everyone—liberal and conservative alike—agrees that at least 15 percent are homosexual. Even if it were fewer, that would make the homosexual problem even worse because it would be an even smaller number responsible for the vast majority of abuse.

    The conclusion is that the vast majority of abuse by children were by men with same-sex attraction. Remove that element from the mix and while you still have a tragedy for those that were abused, you have a much smaller one.

    Ignoring the role of homosexuality when looking for solutions to the Scandal is like saying that to prevent people from dying from gunshot wounds, we have to make safer bullets, while ignoring the guy holding the gun.