Control Freak

A BBC documentary with controls! Always worth highlighting!

The truth about...your medicine cabinet

A one hour documentary looking at the effectiveness of over-the-counter drugs in the UK.
There were several demonstrations looking into the effectiveness of cough medicines (just use honey and lemon) and indigestion treatments (they work but watch what/how you eat) but the control experiment in question was looking at deep heat vs cold creams for muscle injury/recovery. They were actually looking at whether ice vs warm baths help aid muscle recovery (of current interest to me as I have a jogging-related muscle problem)

To do this the presenter had 15 people do the same assault course. 5 of them took a 15 minute hot bath and another 5 took a 15 minute ice-cold bath. Then they followed them over the next few days measuring different factors for assessing muscle pain/recovery. The key thing was that the remaining 5 people didn't take a hot or cold bath after exercise.
The results highlighted the importance of the negative control as hot and cold treatments had virtually the same effect. Those who didn't use either showed significantly poorer recovery. If the negative control had looked the same as the hot/cold treatments we could have concluded neither treatment has an effect but now we know hot/cold treatment is better than nothing!

It's not the perfect experimental set up but I think for a TV show this is the right level and the results hopefully showed casual viewers why the control was important.

The presenter hosted an episode on sugar vs protein diets with his identical twin last year so he clearly likes to get the concept of controls across. Although it seems his twin wasn't taking part in the experiments this time. I guess they decided a higher "n" value was more important than controlling for genetic variance :P


The show itself was surprisingly quite interesting It was somewhat disturbing how many ailments are focused on treating the symptoms when adjusting your diet would prevent them happening in the first place eg diet can solve the need for vitamin supplements and indigestion remedies. It does concern me how we (and I know I'm guilty of it) look for an easy fix rather than a long term beneficial solution. Stubborness, I guess.

Control Freak - how did I get that hangover?

Recently I had an unpleasant allergic reaction to beer. Not in the "I had too much of it" way but more in the "it caused severe congestion, sinus blocking and even swollen eye-lids (not the result of a fight outside the pub)" way. It's not necessarily the alcohol and can be anything from histamines to wheat to some random ingredient in a beer that my body dislikes.

Control Freak

The BBC has been on a roll  showing some experiments on TV of late - I'll try and cover Horizon's "fat vs sugar" . I stumbled across an even better example yesterday. The show is called "Inside the animal mind" by presenter Chris Packham  (who i still remember as the "really wild road show" presenter from decades ago). I was watching it mainly because i was curious as to see how animals view the world differently - something they achieve quite well. What I wasn't expecting was for them to be conducting experiments and actually explaining the concept of experimental controls.

I'll list a couple of examples

• When testing whether a wolf or dog has a different hierarchy for responding to visual or olfactory stimuli - they had an experiment where food was present in two cups first then followed up with an experiment where the food was only in one cup. They also conceded the wolf used wasn't truly wild.

• When testing whether strong magnets deter sharks (due to their magnetic sense) they placed tuna in the centre of a circle of strong magnets. In case the sharks were just apprehensive of black circles they had a circle of bricks (identical in appearance to the magnets) with tuna in the centre. These two circles were side by side - while the sharks repeatedly took tuna from the control circle, they never never took tuna from the magnetic circle.

There were several other neat little experiments where controls were mentioned or limitations clearly pointed out. They also liked to point out that n numbers are vital. The more times you conduct an experiment the more accurate the results become.

Basically my inner control freak was very happy with this show. There appears to be at least one additional episode so I look forward to seeing more experiments.

Control Freak

Sometimes I don't just obsess over the lack of controls on TV - I also like finding controls for mundane events in life. When the mild peril of "St Jude" threatened last week I had to put some new trainers on as my usual ones were wet from the previous night. My girlfriend suggested I should apply some waterproofing to them. I was skeptical so being a scientist I decided to conduct an experiment as follows;

a) Only one trainer was waterproofed, the other acted as a negative control.

b) It would be a blind experiment in that I wouldn't know which trainer was the test or control. It also meant I didn't have to apply the waterproofing.

I then walked into work and judged which shoe was the most wet. This was measured by looking at how much water was on each trainer.One had a lot of raindrops on it - the other had none. If "St Jude" had lived up to the hype I could have drained my socks into a measuring cylinder and judge wetness by volume of water from sock (assuming my feet are evenly sweaty).

Once I had the results I informed my "assistant" and she revealed which trainer had been waterproofed.
I can conclude that the waterproofing does indeed work. What's more tricky is finding a way to justify my girlfriend waterproofing the other trainer in the name of science.

*I assumed I didn't have some foot bias towards puddles but could have got around this by conducting the same walk with the waterproofing on the opposite foot (it would have to blind again). Of course I'd then have to assume there was the same amount of rain over the course of the second journey. A more controlled but less fun experiment would be to pour the same volume of water on each shoe and judge it that way.

Control Freak

It only just dawned on me that I let "Dara O'Briain's Science Club" get away with not using controls in one of their experiments! I guess it's because it was quite entertaining. Fortunately my anal retentiveness resurfaced and I can now call them out on it.

So towards the end of the "invisible worlds" episode they were demonstrating how effective a "hydrophobic" spray was on waterproofing objects. They tested a trainer by pouring water over it and an iPad by submerging it in a tank of water. The water bounced off the trainer and the iPad continued to work underwater quite happily. Amazing stuff but without the control it's meaningless. How do we know the trainer wasn't waterproof without the spray being added? How do we know iPad's are so well made that they work under water? With a control, that's how.

So the experiments should have been like this (as a minimum);

A pair of trainers; one sprayed with the hydrophobic can, the other not sprayed at all. Pour a jug of water over both of them. If the unsprayed trainer gets wet we know the spray works.

Two iPads; one sprayed with the hydrophobic can, the other not sprayed at all. Place both of them in the same tank of water and see whether they both shut down or stay on. Any difference can be attributed to the spray (or lack of).

Now I can understand them not wanting to kill an iPad  (especially as a licence fee payer) but the trainers would have dried off eventually.

EDIT: If a video of it turns up on youtube, I'll link it. There isn't one at the moment at the iplayer clip will shortly expire.

Control Freak!!!

I'm going to try and post these whenever I encounter them. One of my gripes, as a scientist, is when anything is presented as a "scientific truth" but lacks the most basic of scientific principles - a control.
Without a control you have no idea what is actually causing an effect or whether the effect is merely the result of the experimental procedure itself. If your test is different from your control(s) then you can claim there is a significant difference.
I've touched on the subject before and think it's useful to try and point out other examples. It should hopefully appeal to the anally retentive scientists who read and help make non-scientists aware of the concept and allow them to be a little more cynical of "facts" that are presented to them on TV/media.

The 5 second rule - tested.

The BBC made a nice little video "testing" whether the "5 second rule" had any merit. Here's the video (not sure if outside UK readers will be able to see it?)

http://www.bbc.co.uk/news/magazine-21945313

Basically it's not a good idea as the food samples dropped on the floor for 5 seconds all had a lot of nasty bugs on them after culturing them overnight on bacteria friendly plates.

 Fortunately the "mum" points out that the cleanliness of your own floor is also an important factor.

There is one flaw with the experiment though as they don't have a true negative control - unless I'm misunderstanding their "0 second" test. Basically they need to put a sample of bread (or apple) that hasn't been dropped on the floor. It could well be that the culture results are from the food itself and not the floor. They could also do a floor imprint as well while they are at it. If there's as many cultures on the plate for the sample that never contacted the floor then the contamination is inherent in the food. In which case the 5 second rule still applies! There's still hope.

Still a commendable bit of everyday science on the BBC.