My point in including the secondary source was not to comment on the original research findings but to comment on the spin put on them by the person quoted by the secondary source. I am sorry if she was misquoted but I have nothing against her personally. I used the quote only to make a point. I don't remember for sure but I don't believe she had any part in the research being discussed. If I was taking exception to the results of the study itself, I should have cited the primary source.
My point was that you are missing the point of nomothetic research if you say, "it worked for some and it didn't work for others". It's like saying if half the sample did worse on the treatment and half the sample did better (for an overall "no difference" outcome) that that is a great outcome for half of the group and a bad outcome for the other half. That would ignore the effects of chance which is what the nomothetic approach is all about. If 1000 people start to flip coins, after one flip approx. 500 will have flipped heads. On the next flip it is down to 250. Then 125, 62 or so, then 31 and about 15 and then about 8 then 4 then 2 then there may be one person who has flipped heads all 10 times. Instead of believing that person has the power to flip heads at will, I believe that, given that situation, one of those thousand people is likely to flip heads 10 times and it has nothing to do with their head flipping ability (supernatural or otherwise). By chance, some will seem to do better in any trial. What we need to be able to do in research is separate chance from the actual effect. Of course, there could be individual differences in response to a treatment and those can be isolated in idiographic research. I would also expect, if a number of people have such an effect, to see some kind of noticeable outcome in nomothetic research, too. Rick Dr. Rick Froman Professor of Psychology John Brown University 2000 W. University Siloam Springs, AR 72761 [EMAIL PROTECTED] (479) 524-7295 http://www.jbu.edu/academics/sbs/faculty/rfroman.asp -----Original Message----- From: Mike Palij [mailto:[EMAIL PROTECTED] Sent: Tuesday, February 28, 2006 5:45 PM To: Teaching in the Psychological Sciences Cc: Mike Palij Subject: Primary vs. Secondary Sources (was re: Why indeed! On Mon, 27 Feb 2006 06:43:50 -0800, Rick Froman wrote: >>From the last paragraph of: http://www.msnbc.msn.com/id/11532184/ > >"Dr. Mary Jo DiMilia, an integrative medicine physician at Mount >Sinai Medical Center, says none of her patients have asked about >foregoing calcium, and she's not giving up the glucosamine she's >relied on to relieve arthritis pain for the last two years. 'If it works >for me,' asks DiMilia, 'why should it matter that the study didn't >find benefit for all patients?'" > >Dr. Rick Froman I assume that the above quote was provided to highlight either the lack of rationality on Dr. DiMilia's part or perhaps the inability of some physicians to respond adequately to empirical results (a point I'm willing to concede) or something similar. However, I'd like to take this opportunity to provide a "teaching moment" by focusing on various issues that we might want to keep in mind when we look at medical research, especially if we only read media accounts of the original research: Rely on Primary Sources instead of Secondary Sources: although it is tempting to think that an article in a newspaper or magazine or a website or a news program might be unbiased and comprehensive in its presentation of a subject, we need to remember how often secondary souces distort, misrepresent, or just get wrong specific details (Little Albert anyone?), which is why we tell our students not to rely on secondary sources but that they should instead go to the primary source. Below is a quote from the New England Journal of Medicine's abstract for the article described in the MSNBC article (I reproduce only the last couple of paragraphs): |Results The mean age of the patients was 59 years, and |64 percent were women. Overall, glucosamine and chondroitin |sulfate were not significantly better than placebo in reducing |knee pain by 20 percent. As compared with the rate of |response to placebo (60.1 percent), the rate of response to |glucosamine was 3.9 percentage points higher (P=0.30), |the rate of response to chondroitin sulfate was 5.3 percentage |points higher (P=0.17), and the rate of response to combined |treatment was 6.5 percentage points higher (P=0.09). The |rate of response in the celecoxib control group was 10.0 |percentage points higher than that in the placebo control |group (P=0.008). ********For patients with moderate-to-severe |pain at baseline, the rate of response was significantly higher |with combined therapy than with placebo (79.2 percent vs. |54.3 percent, P=0.002)*****. Adverse events were mild, infrequent, |and evenly distributed among the groups. [Note: Emphasis added; Also "combined therapy" refers to the combination of Glucosamine + Chondrotin). |Conclusions Glucosamine and chondroitin sulfate alone or in |combination did not reduce pain effectively in the overall group |of patients with osteoarthritis of the knee. Exploratory analyses |suggest that the combination of glucosamine and chondroitin |sulfate may be effective in the subgroup of patients with |moderate-to-severe knee pain. (ClinicalTrials.gov number, |NCT00032890 [ClinicalTrials.gov] .) And from the last paragraph of the article: |How should our results affect the treatment of symptomatic |osteoarthritis of the knee? Our finding that the combination of |glucosamine and chondroitin sulfate may have some efficacy in |patients with moderate-to-severe symptoms is interesting but |must be confirmed by another trial. To be clear, here are a couple of the main results: (1) There is a main effect of medication relative to placebo but this appears to be due to Celebrex's effect (i.e., an increase of 10% in people reporting improvement relative to the 60% reporting benefit due to placebo [which the authors point out is a huge placebo response rate]. Note that the combined Glucosamine+Chondritin (G+C) treatment produced the next largest effect, namely a 6.5% increase in people reporting benefit relative to placebo. Is 6.5% vs 10% that large of a difference? Apparently for statistical significance but one might ask what is the statistical power for this comparison. (2) There is an interaction of between treatment type (e.g., placebo, Glucosamine, Chrondritin, G+C, and Celebrex) and degree of initial degree of knee pain -- G+C appears to help people with with moderate to severe symptoms as measured by 20% decrease in WOMAC pain score.. I may have missed it in the MSNBC article but was the severity of Mr. Milia's ostearthritis identified? (Note: the p-value for Celebrex for this group was 0.06). Now, I'm not a big fan of alternative/compementary medicine (I do admit to a fondness for placebo effects) but it seems to me that if a person suffers from moderate to severe knee osteoarthritis taking a G+C supplement may actually be helpful -- which might be the point that Dr. Milia was making above (especially since Celebrex doesn't make it to the "magical 0.05 level" for this group). Finally there is the issue of cost of taking a G+C supplement, relative to Celebrex. Checking Walgreens for their prices: Celebrex 200mg (dosage used in study): 60 capsules= $189.99 G+C combo (G=250,C=200): 42 tablets=$5.00 (est. 60=$7.15) (NOTE: above G+C doses are "regular strength", same as in study) Hmmm, if one has moderate to severe knee osteoarthritis, would one want to pay $7.15 or $189.99 (that is, if one doesn't have a prescription insurance plan for Celebrex plus cost of getting a doctor's prescription -- let's ignore the potential side-effects of Cox-2 inhibitors like Celebrex until after the trial; see, for example: http://www.miami.com/mld/miamiherald/living/health/13975911.htm Then again, given that there was a 60% placebo response rate in the study, maybe we should stock up on those little white pills with inert substances (not "sugar pills", we have a big enough problem with obesity in the U.S. ;-). In general, we should be critical and skeptical of research results because (a) all research has significant limitations (if not significant flaws) and (b) scientific knowledge is tentative, subject to revision or reversal as new results from better research is produced. Oh yeah, and don't believe everything you read in the newspapers or see on TV. -Mike Palij [EMAIL PROTECTED] New York University --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED] --- You are currently subscribed to tips as: [email protected] To unsubscribe send a blank email to [EMAIL PROTECTED]
