Tampilkan postingan dengan label Evidence. Tampilkan semua postingan
Tampilkan postingan dengan label Evidence. Tampilkan semua postingan

Kamis, 16 Februari 2012

Bias, Part 2.

I know what I like! Here's Genesis from their "Seconds Out" concert.



If you like/trust somebody/some organisation, they can do no wrong. Everything that they say/do is interpreted in the best possible light.

If you dislike/distrust somebody/some organisation, they can do no right. Everything that they say/do is interpreted in the worst possible light.

I like/trust people. I give people the benefit of the doubt. Three strikes and they're out, though! Ditto for tradespeople and small businesses. To minimise the chance of getting ripped-off, I use personal recommendations and sites like http://www.checkatrade.com/

I don't dislike large organisations, but I don't trust them. I consider big businesses to be soulless money-making machines, and governments to be incompetent and/or corrupt (to varying degrees) people-ruling machines.

This post is also about arguments on the internet. My plea is this:-
Please support your likes/trusts and dislikes/distrusts with evidence if at all possible. If you want to get rid of something that you dislike/distrust, please suggest a workable alternative.

Jumat, 02 Januari 2009

Elvis lives!

This bloke said he saw Elvis down the chip shop. What? You mean he was mistaken or lying? Surely not!
Regularly, you read or hear:- "Aspartame gives you cancer!" "Meat gives you cancer!" "Crisps give you cancer!" "Coffee gives you cancer!" "Coffee doesn't give you cancer!" "Coffee gives you cancer!" and so on and so forth...... What are we to believe?

In terms of Diet & Nutritional information, there's a hierarchy of credibility. Here's a rough list of credibility, starting with least credible and ending with most credible.

Inexpert opinion. Basically, anyone can say anything (especially on the internet) but that doesn't make it true. This includes anything that I say, which is why I try to back up what I say with evidence from higher up the pile.

Anecdotal data/testimonials. Just because it worked for Joe or Josephine doesn't mean that it'll work for anyone else. There's also the placebo effect e.g. Nothing acts faster than Anadin (so I use nothing!)

Expert opinion. Even "experts" with lots of letters after their names get things wrong and have personal biases, hence the controversies over MMR, HIV/AIDS, Cholesterol etc.

In Vitro (in glass) studies. What happens in Petri dishes/test-tubes etc doesn't necessarily happen in humans.

In Vivo (in life) animal studies. What happens in rats/monkeys etc doesn't necessarily happen in humans.

Epidemiological (population) studies. A being associated with B doesn't necessarily mean that A caused B, as the association may have been due to random chance or due to both being caused by C, D, E........Z etc.

Case studies. The number of subjects is usually quite small and sometimes just 1.

Small and/or non-randomised and/or unblinded and/or non-placebo-controlled and/or non-crossover trials.

Large, randomised, double-blinded, placebo-controlled crossover trials.

Meta-studies of large, randomised, double-blinded, placebo-controlled crossover trials.

Even the last 2 items aren't perfect. Study outcomes can be manipulated by tweaking the methodology (e.g. using pre-trial screening) so if a trial is funded by a drugs company, the methods used and results obtained need to be examined very carefully. In addition, the abstract can misrepresent the full study. Here's an example: Intensive lipid lowering with atorvastatin in patients with coronary heart disease and chronic kidney disease: the TNT (Treating to New Targets) study. The Conclusion reads: "Aggressive lipid lowering with atorvastatin 80 mg was both safe and effective in reducing the excess of cardiovascular events in a high-risk population with CKD and CHD." because there was a 15-32% reduction in major cardiovascular events. Wow, that's impressive! What the abstract failed to mention was the fact that there were 26 more deaths in the 80mg group than in the 10mg group. What's worse? Having a major cardiovascular event or being dead?

In conclusion, when you read something in the media, do some research of your own before accepting it as fact. Use Google, Wikipedia, PubMed and the Cochrane Library.