## Thursday, January 19, 2012

### Crap health data on the web

There is a ton of crap health data on the web. Here is a screen grab from livestrong.com.
Notice the caclulation for calories burned:
"Calories burned by exercise = (METs x 3.5 x weight in kg) / 200 x duration in minutes"
If you don't understand math that might make sense to you, but, any of us familiar with math will tell you the equation is crap. Essentially with this equation the longer you do something the fewer calories you burn.
1*3.5*100 = 350/200*1 = 1.75
1*3.5*100 = 350/200*2= 0.875
So if you do an activity for 1 minute you burn 1.75 calories and if you do an activity for 2 minutes you burn 0.875 calories.
Lets look at their example equation:
(5 x 3.5 x 81)/200 x 60 = 425 calories burned.
5*3.5*81=1417.5
200*60=1200
1417.5/1200=0.0118125 not 425
The equation should be:
"Calories burned by exercise = (METs x 3.5 x weight in kg) / (200 / duration in minutes)"
(5 x 3.5 x 81)/(200 / 60) = 425 calories burned.
I am not picking on Livestrong. I noticed the error because I like the website and I use it. The point is that even people or websites with the best intentions who appear to be knowledgeable about the subject make errors and if you try and plan a diet using the data from Livestrong you end up making bad plans.
We need to double check our data. Livestrong does not have a "contact webmaster" link, so I couldn't copntact them and let them know they made an error. Often when I report an error I get an e-mail flame in return. Sometimes I am ignored and occasionally the webmaster thanks me for pointing the error out.
Everyone makes mistakes. Everyone and there isn't a problem with making mistakes. Making mistakes is good because it helps us become better people. At the same time people need to double and triple check every piece of data they use in their decision making process.
It is easisest to make mistakes when we have bad data.