Posts Tagged ‘bad health stats’

h1

3. Stuff Ups 1

June 14, 2013

You go to the doctor with lower back pain.

bad back

The doc recommends an MRI scan. A problem is identified and an operation, perhaps, recommended. But here is the problem. The back problem identified in the scan may not be the cause of the pain.

Risks: health screening

In maths this is called FALSE ATTRIBUTION.

You get all the pain – financial and physical – but no gain.

You will find a very interesting discussion of this problem The Health Report, Radio National, ABC.

Dentists suffer a higher incidence of lower back pain … Maybe from prancing around in towels in front of mirrors. Wait. That was only a small sample of 10 paid dentists.

No conclusion can be drawn.

h1

5. Not the Full Story

June 13, 2013

TV Kills was the headline that raced around the world as a result of this study.

TV shock

As New Scientist pointed out:

The asked 8800 people about their health, lifestyle and television watching behaviour, and then followed them over the next six years, during which time 284 of them died. Among people who spent more than 4 hours a day in front of the TV, it found, the risk of their dying within the period of the study was 46 per cent higher than among those who watched less than 2 hours a day.

couchpotato

The error is confusing CORRELATION with CAUSATION. The risk might involve the sitting rather than TV. Or it could be that those who sit in front of TV longer are not well.

THIS IS A COMMON AND DANGEROUS ERROR INVOLVING HEALTH STATISTICS

bones

Now that we have more screening tools we must be more cautious.

Angelia Jolie had her breasts removed because of testing positive for the BRCA 1 and BRCA 2 genes, which are linked to an increased risk of Breast Cancer.

bow

This is her decision. Anyone facing breast cancer would seriously consider this option.

Angelina

BUT, be wary if you face this decision.

asthma

Think of Asthma. If we started our research into asthma looking for asthma genes we would have found them.

Genes create a pre-disposition for Asthma (hence the correlation) but they do not cause asthma.  The dust mite, pollen, cat, dairy and other allergies cause asthma. If researchers had concentrated on genes alone our knowledge of asthma would be limited.

prisoner

 Another study showed that 80% of prisoners in Australia smoke. Isn’t it obvious? Smoking causes criminal behaviour!!!!!

h1

8. You’re All gonna Die 1

June 13, 2013

Red wines good for you. Red wines bad for you. Red wine causes cancer. Ditto coffee etc. What’s going on?

Here is Ben Goldacre in a TED talk called Battling Bad Science.

Everytime a study finds this or that food is good or bad for you they usually make one huge error.

bones

It’s called a BIASED SAMPLE.

Here is an example Real Men Eat Meat and Die

The study showed that “Men whose red meat intake put them in the top 20 per cent consumption band were 22 per cent more likely to die of cancer in the 10 years of the study, compared to men whose intake was in the lowest 20 per cent. For women, there was a 20 per cent increase in risk.”

The problem is big meat eaters tend also to be big drinkers, smokers, obese and the rest. This study has tried to separate out meat eating from other unhealthy lifestyle choices using the Cox Regression. Mathematical wizardry has produced these numbers but they don’t mean much. meat eat 2

If the study used a control group of drinking, smoking, obese vegans then compaing mortality rates over 10 years would be would be interesting. But where do you find half a million of them????????

lg20eden20hippie

Meanwhile any survey or study of a self-selecting group (eg. newspaper polls among readers) or a pre-existing group (eg. a church group, college students, yacht club, rock ‘n roll club) produces biased and therefore meaningless results.

eg. 9 out of 10 dentists who are paid to say they recommend Oral B toothbrushes is useless information, a study of paid jerks, really.

Look for a RTC or Randomised Controlled Trial. 

Any study that begins a ‘trial of college students found’ (eg. psychology trials) is a BIASED SAMPLE. Look at the lifestyle of college students. How many people in the general population wear beer hats to parties? If you asked 10 beer hat wearing college students their opinion on Oral B toothbrushes they might not even recall the purpose of a toothbrush!

college beer drink hat

Look for big randomised trials.