Tuesday, 10 September 2013

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.

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