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Comment: Link to abstract (Score 4, Insightful) 63

by Michael Woodhams (#47555199) Attached to: UK Team Claims Breakthrough In Universal Cancer Test

Here is the abstract. The actual paper is behind a paywall.

"ROC analysis of [the test statistic], for cancers plus precancerous/suspect conditions vs. controls, cancer vs. precancerous/suspect conditions plus controls, and cancer vs. controls, gave areas under the curve of 0.87, 0.89, and 0.93, respectively (P<0.001). Optimization allowed test sensitivity or specificity to approach 100% with acceptable complementary measures."

The ROC curve has area under it of 1 for a perfect classifier and 0.5 for wild guessing. This is a more useful measurement than the p-value. (E.g. if I look at height vs sex for humans, it won't take too big a sample to get a great p-value for there being a difference, yet classifying people as male/female depending on whether they exceed some height threshold is a very poor diagnostic system.) I don't have much of a feel for how good ROC area of about 0.9 is for a medical test. I'd guess it is good enough to be useful, but you'd not want to rely on that test alone.

Comment: Re:I don't see the problem. (Score 4, Informative) 667

by Michael Woodhams (#47497149) Attached to: Russian Government Edits Wikipedia On Flight MH17

The plane was 10km up. It wasn't shot down by something bought for $50,000 from Bob's Quality Used Implements of Death and Destruction and delivered to you by a courier van. The suspected weapon system requires at minimum one tank sized tracked launcher vehicle, and for full capability it requires three such vehicles. This is way out of Bob the arms dealer's league. Although I'm pretty much guessing here, the missile alone I expect would cost over a million dollars to manufacture.

Having said that, the possibility exists that rebels with military experience seized such a weapon system from an overrun Ukrainian military base.

Comment: Re:Neandertals and light skin (Score 2) 133

by Michael Woodhams (#47374319) Attached to: Tibetans Inherited High-Altitude Gene From Ancient Human

Immune system genes are often under balancing selection - i.e. the rarest alleles are favoured (until, due to this favouring, they cease to be rarest, then other alleles are favoured.) An infusion of new different alleles from Neandertals could be favoured simply because they are different, not because they are evolved to European conditions.

Testing between these hypotheses seems difficult. The 'balancing selection' hypothesis predicts that the genes will readily spread back into Africa, whereas the 'evolved for European conditions' predicts they will not. The problem is that you need some neutral mutations that arose in Europe at the same time as a 'control' for comparison purposes. I'm not sure how to identify such mutations, but I expect it could be done.

Comment: Neandertals and light skin (Score 3, Interesting) 133

by Michael Woodhams (#47374055) Attached to: Tibetans Inherited High-Altitude Gene From Ancient Human

There is another obvious point in history where such a gene transfer could have occurred. European conditions favour light skin, and Neandertals had been hanging out there for some tens of thousands of years before modern humans turned up and so had evolved light skin. These newcomers, having recent ancestry in Africa, were probably dark skinned. Interbreeding could easily have introduced the beneficial-to-European-conditions light skin mutations into the modern population.

My memory of the literature (which I have followed just a little bit, not closely) is that this did not happen - genetic analysis shows that modern Europeans and Neandertals acquired light skin through different mutations. However, Wikipedia says this is still under debate.

Comment: Re:Careful (Score 2) 116

by Michael Woodhams (#47365287) Attached to: Renewable Energy Saves Fortune 100 Companies $1.1B Annually

This is a silly objection. That isn't how payback times are used.

Payback time is a quick indication of return on investment. You then compare that return on investment with the other options available to you, such as leaving the money in the bank.

If you included interest rates in payback time, you'd need to be constantly adjusting it as rates changed, and it would differ for different entities depending on their access to finance. Instead you keep it simple, and each entity has its own idea (based on circumstances and current interest rates) of what the effective payback time is of leaving the money in the bank (or not borrowing it, or investing it in other opportunities.) (For example, a start-up is likely to require a very short payback time - they're strapped for cash and are trying to get their Big New Idea to market where they hope it will make a fortune. Up-front money is then very expensive compared to down-the-road money. For them, it may make sense to lease a supercomputer even if buying it would have a two year payback time.)

What is missing from this analysis is depreciation of assets. After 6.4 years, money in the bank will have depreciated much less than the solar cells. Payback time is a rough guide - it tells you whether it is worth your while doing a more detailed analysis including finance cost, depreciation, tax implications etc.

Comment: Re:Show me the money! (Score 4, Insightful) 441

They aren't. They're using an established term "energy payback". The authors wrote an analysis which will be useful to many people but used the word "payback" in a way which does not match your preconceived notion of how it should be used. For this, you label them "charlatans".

So all the people interested in energy payback times should not be able to publish or read about it because you've claimed ownership of the word "payback" and won't license them to use it? They should use a less clear term to express their meaning because otherwise some random idiot who reads technical papers might make the leap "payback = money", despite the term "energy payback" being self explanatory?

Had you argued that because this is "energy payback" rather than financial payback, it isn't worthy of being reported on Slashdot, I could respect your argument. Instead you label people charlatans because what they discuss is not what you're interested it.

Comment: Re:Who is that? (Score 4, Insightful) 268

by Michael Woodhams (#47312961) Attached to: Wikipedia Editors Hit With $10 Million Defamation Suit

Oh good, I'll just print up a bunch of fliers saying you torture kittens and set fire to orphanages and post them around your home town. Because nobody has heard of you and I'm not a publicly listed company, it will be 'opinion' rather than 'libel'.

I have no idea whether this guy's claims are justified, but neither do you. My liking Wikipedia does not therefore mean that the facts or the law are on the side of Wikipedia.

Comment: Prediction (Score 4, Insightful) 547

When El Nino leads to a new record high temperature by a large margin (for argument's sake, in 2015), the denialists will quietly adopt this as their new standard for 'normal' and in 2025 they'll be saying "warming is a hoax because temperatures haven't risen on average since 2015."

http://xkcd.com/1321/

Comment: Re:Not the right way anyway (Score 1) 583

by Michael Woodhams (#47105723) Attached to: Google Unveils Self-Driving Car With No Steering Wheel

How about a detachable luggage compartment (boot/trunk)? You don't own the car, but you have your own luggage compartment in which you keep your miscellaneous crud. Call a car, attach your compartment, drive to the mall, detach compartment, shop and fill compartment, call another car, go home, detach, unpack at your leisure while the car goes on its next mission.

"Just the facts, Ma'am" -- Joe Friday

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