I thought I would use this to discuss two rather different topics of relevance to medicine in general.
- The statistical relevance of non-occurrence of an event
- The problem of decorum versus thuggery
In this case there were no negative responses amongst 13 events. This problem has general relevance in medicine. Commonly, in clinical studies there are no observed events in a large number of patients. Forgetting for the moment that study patients might not reflect real-world patients, and that results of studies are often manipulated, it is interesting to examine the statistical meaning of non-occurrence. For example, if there are no deaths following liver biopsy in 200 consecutive patients in a particular hospital, how confident can we be about the mortality rate? If no patients (of 13) die in a Phase I study of an experimental drug, what does this mean? If the public relations officer of a bisphosphonate manufacturer claims that there were no cases of Osteonecrosis of the Jaw (ONJ) in formal clinical trials (n=3000) what are the confidence limits for the rate of ONJ within the population (assuming no-cheating, proper followup, and real-world similarity of trial patients)?
If the true rate of occurrence of an event in the population is R, then the probability P of non-occurrence in n consecutive patients is:
P = (1 - R)n
We can solve this for n as follows:
n = (log P)/log(1 - R)
This enables calculation of the number of consecutive non-occurrences needed to infer a low rate of occurrence R at a chosen P value. To the naive, the resulting numbers may seem surprising. If there are no deaths in 13 patients in a Phase I trial, then all we can say is that the likely death rate is less than 20% (at P=0.05). To infer a death rate in our Phase I study of not more than 1% we need to observe 299 cases with no death. I wonder whether patients in Phase II trials are provided with such information, either numerically or in spirit?
On the problem of decorum and swearing
I was interested in some of the responses I received. In the words of David Kern:
When you're in an argument with a thug, there are things much more important than civility. I do not like incivility. Yet, I like thugs even less.My feeling is that our profession cares a great deal more about decorum and a sort of "pseudo-politeness" than we do about actions that are truly immoral, anti-science, and damaging to patients. Patients seem to care rather more about scientific honesty than we imagine. I have written previously of the quotation by the Irish priest Steve Gilhooley about the relation between decorum and thuggery. The quotation was delivered as part of a sermon on El Salvador. Gilhooley spoke passionately from the pulpit:
"I said to them, '70,000 people have been butchered and none of you gave a shit.'"Much of Gilhooley's feelings about the church would apply to the current sad state of medicine. Says Gilhooley [of the church]
There was silence. A priest had sworn in the pulpit.
"And the reason I know none of you gave a shit," he continued, "was because none of you fell off your seat when I said '70,000 had been butchered', but nearly all of you fell off your seats when I said 'shit'."
"There are those who would rather hide the truth. Those whose priorities have become so skewed that they would protect [sexually] abusive priests before they would protect those who fight for justice and transparency. These are the people who are really in control in the Church. Well, let them get on with it. Let them bury it in the ground, and then we'll all start something else."The offense caused by words depends on the priority we ascribe to various things. According to the "Hitchhiker's Guide to the Galaxy," the most offensive word in the universe is "Belgium." A journalist in the Melbourne Sunday Age (29.6.2003) provided an eloquent example of the significance of words following Greg Rusedski's Wimbledon soliloquy during his tennis match with Andy Roddick:
"As this is a family paper, both major and minor obscenities have been replaced by the names of birds. The result should be informative and educational."
"I can't do anything if the crowd albatross calls it. Absolutely vulture ridiculous. At least replay the point. Robin ridiculous, falcon ridiculous, budgie ridiculous. Some lesser-crested grebe in the crowd changes the whole match and you allow it to happen. Well done, well done, well done. Absolutely muttonbird..."
Here are some varied educational links:
- Stupendous BBC/Advertising Standards Authority report on swearing - an impact analysis listing all the bad words (complete with graphs and statistical analysis)
- Great piece on the evolution of swearing by a Geoffrey Nunberg (a linguist at UC Berkeley)
- Why we curse. What the F***? by Steven Pinker, Harvard (fantastic, a must read).
- Clin Psych blog on the Pinker article
- How stuff works: Swearing
- Swearing in other languages
- West Side woman faces jail time for swearing at toilet: Pennsylvania Times-Tribune. Dawn Herb was facing jail for swearing at her overflowing toilet in her own home. She was overheard by an off duty police officer who heard her yell: "Are you f***ing retarded? Get me the f***ing mop." Patrolman Gilman said he then yelled, "Watch your mouth", to which the person replied: "F*** off.". She was later acquitted.
- College Teacher fired for saying F___ in class: Inside Higher Education
- Devil's Kitchen: On swearblogging (an excellent, intelligent UK political blog which includes a great deal of swearing).
- Ben Goldacre: Sweary Mary