Re: Marijuana
David C. Ullrich wrote: considerable benefit for neurogenic bladder problems, I did not know that, but I know that the topic is of considerable interest to people with various other conditions. Yes, recent work at the National Hospital of Neurology and Neurosurgery in London, UK has shown that two cannibinoids administered in a spray considerably reduce urinary frequency and the number of time PwMS have to get up to pee during the night (a big problem). The researcher I was talking to said that there are cannibinoid receptors in the bladder and the cortex but not in the micuration control areas of the brainstem nor in the spinal cord. As is the fact that the Supreme Court seems to have decided that pi = 3 again... More like -6. Here I get a little lost again. Exactly what does it mean to say the relative risk is 4.8? I assumed it meant event A happened 4.8 times as much as would be expected if the two events were unrelated. And here again I'm _totally_ lost. Okay, put it like this: Of 1086240 trials, A happened in 17484 of them, B happened in 124 and both A and B happened in 9. I really need to know how to how to calculate the statistical implications here. Please someone help me! What I want to know is what is the correlation between these two event? Most importantly, how statistically significant is the result? Can any reasonable conclusions be drawn from these data - esp, in view of the small dataset size? Take care, Paul All About MS - the latest MS News and Views http://www.mult-sclerosis.org/ = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Marijuana
David Petry wrote: Keep in mind that correlation is not the same as causation. That's of particular importance in a study like this one. That is, if people are taking marijuana to treat pain and general discomfort, and if heart attacks are preceded by pain and discomfort, then there will be a strong correlation between marijuana use and later heart attacks, but it won't be proof of causation. I know the study is flawed in ever so many ways. I just want to get at the statistical implications. I wish I hadn't memtioned marijuana or the trial. Please help me to find the appropriate statistical test (e.g. two-tailed t-test, Spearman Rank correlation, chi2 test or whatever) and help me work out the statistical significance of any correlation between events A and B where: In 1086240 trials, A happened in 17484 of them, B happened in 124 and both A and B happened in 9. Is there a statistical association between A and B? How significant is that association? I would be ever so grateful if someone could help. Take care, Paul All About MS - the latest MS News and Views http://www.mult-sclerosis.org/ = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Marijuana
There was some research recently linking heart attacks with Marijuana smoking. I'm trying to work out the correlation and, most importantly, its statistical significance. In essence the problem comes down to: Of 8760 hours in a year, 124 had heart attacks in them, 141 had MJ smokes in them and 9 had both. What statistical tests apply? Most importantly, what is the statistical significance of the correlation between smoking MJ in any hour and having a heart attack in that same hour? What is the probablity that the null hypothesis (that smoking marijuana and having a heart attack are unrelated) can be rejected? How reliable are the results from a dataset of this size? I'm not very literate in maths and stats - please help me out someone. I'm interested in this research from the perspective of medicinal marijuana. Thanks and take care, Paul All About MS - the latest MS News and Views http://www.mult-sclerosis.org/ = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Marijuana
Steve Leibel wrote: So the people who died from heart attacks weren't even considered in the study. Perhaps of all the people who had heart attacks, recent mj use was statistically correlated with saving their lives. That would be consistent with what you just described. So the methodology sounds bogus. That's not all - the MJ users had an excess of males, cigarette smokers and obese people - all increased risks for myocardial infarction. These articles rarely show statistical significance and it's hard to get hold of the full text without paying loads for it - besides, the full text might not quote p values. I want to know how statistically significant the association is, even given the studies obvious weaknesses. I need to know how to calculate a p value. If anyone could help it would be of great value to myself and a number of other PwMS. Thanks and take care, Paul All About MS - the latest MS News and Views http://www.mult-sclerosis.org/ = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Marijuana
Thanks for replying, David. I'll try to frame the problem better. First, I shall explain my motivations. There has recently been some research that implied that smoking MJ increased risk of heart attack in the hour following the heart attack. I haven't got the full text of the article - I've just seen the abstract, the press releases and resultant press coverage. There is a lot of dodgy research research and I want to know how statistically valid this research is. As you can imagine this topic is of great interest to people who use medicinal marijuana for multiple sclerosis as it has considerable benefit for neurogenic bladder problems, neuropathic pain and muscle spasms. The headline that MJ may increase heart attack risk in the hour following smoking it is extremely pertinent to people with MS. This explains my motives. This is not homework - I have MS. So the research says that of a large number of people who had heart attacks at a centre, 124 people had used MJ in the year preceding the HA. Of these 9 reported that they had used MJ in the hour preceding the HA. All MJ users were questioned on the frequency with which they used MJ. The relative risk was reported as 4.8 - I used this to back-calculate that the average number of MJ usages per year rounded 141 - (9/n)/(115/(8760-n)) = 4.8 I see an immediate mistake in what I wrote before - I have used the average Med MJ smokes but the total heart attacks. Restating the problem: Event A is smoking MJ. Event B is having HA. Let's assume that both events can only happen once per hour and that each person only had one HA. Of 1,086,240 hours, A happened 17,484 times, B happened 124 times and both A and B happened 9 times. What I want to know is what is the correlation between these two event? Most importantly, how statistically significant is the result? Can any reasonable conclusions be drawn from these data - esp, in view of the small dataset size? I would appreciate being corrected. Take care, Paul All About MS - the latest MS News and Views http://www.mult-sclerosis.org/ David C. Ullrich wrote: On Thu, 14 Jun 2001 15:22:25 +0100, Paul Jones [EMAIL PROTECTED] wrote: There was some research recently linking heart attacks with Marijuana smoking. I'm trying to work out the correlation and, most importantly, its statistical significance. In essence the problem comes down to: Of 8760 hours in a year, 124 had heart attacks in them, 141 had MJ smokes in them and 9 had both. What statistical tests apply? None. What you've said here makes no sense - what does it mean for an _hour_ to have MJ smoke? If you're actually reporting on actual research it would be interesting to know what the actual researchers actually said - if there's actual research out there that talks about the number of hours in a year containing smoke that will be remarkable. If otoh this is a homework question you should quote the question more accurately. (If the homework question _really_ reads _exactly_ the way you put it then you should complain to whoever assigned it that it makes no sense.) Most importantly, what is the statistical significance of the correlation between smoking MJ in any hour and having a heart attack in that same hour? Now this sounds more like you're talking about one person. This is an actual person who actually had 124 heart attacks in one year? I doubt it. What is the probablity that the null hypothesis (that smoking marijuana and having a heart attack are unrelated) can be rejected? How reliable are the results from a dataset of this size? I'm not very literate in maths and stats - please help me out someone. I'm interested in this research from the perspective of medicinal marijuana. Fascinating topic. If this is not actually homework you need to explain the question much more accurately. Thanks and take care, Paul All About MS - the latest MS News and Views http://www.mult-sclerosis.org/ David C. Ullrich * Sometimes you can have access violations all the time and the program still works. (Michael Caracena, comp.lang.pascal.delphi.misc 5/1/01) = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
