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About Prometheus

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    Building statistical models for Raman spectroscopy.

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  1. Trouble shooting is one of the most important aspects of programming. I would recommend you go through your code line by line and check it does what you think it does. First instance what do you think rand(0,1) is doing? If you run just this line do you get a value of x you expect or something else? Type help rand into your command window to see why it might not be doing what you expect and some suggested alternatives.
  2. I often hear that Rayleigh scattering is several orders of magnitude more common than Raman scattering; for instance here is one description. However, i have not come across any explanations as to why this is so. I presume it has something to do with Raman being an inelastic process. Does anyone know of any quantum or classical derivations showing why Rayleigh is so much more common than Raman scattering?
  3. So you want flip a coin d times and plot the outcomes for different parameters of that coin? Or do you want to run a monte carlo simulation to check the probability of getting n heads from d flips? What have you tried so far?
  4. Cost, death, benefit analysis...

    Yep. CPR isn't assessed by NICE though. If they did that US study i linked to earlier suggests they wouldn't offer it to octogenarians at current thresholds.
  5. Cost, death, benefit analysis...

    But the doctor isn't just concerned with THE patient: they will have many patients. Any decision regarding one patient will likely have an impact on another patient, including financial decisions. Doctors will already sometimes triage patients in extreme situations, choosing not to save one person in order to focus on someone else more likely to survive. Financial limits exist and they force these life and death decisions. Yes each person has paid into the pot, but it's not an infinite pot and paying in shouldn't mean you can take out so much it's to the detriment of others. If you want to pay into your own pot we have private healthcare insurance too.
  6. Cost, death, benefit analysis...

    The counter argument is that sustaining a life will cost the healthcare provider money. This money is not an infinite resource; by spending money on keeping one person alive necessarily impacts upon the care, and even the life or death, of another person. At some point it will become unreasonable to sustain one life at considerable cost: the money would do more good and save more lives spent elsewhere. These things are already considered in the UK when deciding whether to licence the use of certain drugs. The question is whether to extend it to DNR decisions. There is always a case that resources can be diverted away from, say, military spending (a common argument in the UK) to avoid such problems but i think that's just kicking the can down the road. I'm not sure it would save much money. Many signing DNR go on to die relatively soon anyway (can't remember the figures right now) and i would hope we divert resources into good end of life care (currently lacking in the UK) which might up eating up any financial savings. However, if it improves end of life care i think this would be preferential.
  7. How to calculate the Moments of a new PDF

    Try this link. It's an extract from a book (seems OK); you should be able to find the details of it for a full reference. I googled 'equation for fourth standardised moment'.
  8. True Meaning of Life

    We create meaning because the human brain is an organ that constructs meaning: presumably it benefits us as a species. It's just another thing the universe does when the conditions are right for it: another swirl in a mote of dust , no more or less real than the formation of spiral arms in galaxies. We could attempt to deconstruct it and ask what is going on, but i think it would be a mistake to treat it as an illusion. At some point though you just got to try to enjoy the ride.
  9. How to calculate the Moments of a new PDF

    You can find moment generating functions in just about any book on fundamental statistics, something like A First Course in Probability by Sheldon Ross. I'm not sure of a specific book with the specific equations you want. There are plenty of books on google you can check - they'de be under moment generating functions or MGFs section (or maybe under a thorough chapter on expectation).
  10. How to calculate the Moments of a new PDF

    Yes. This is essentially the same as working out the first four terms in a moment generating function. -3 from the last one if you want the excess kurtosis rather than vanilla kurtosis for some reason. This page might be helpful.
  11. How to calculate the Moments of a new PDF

    By develop the pdf do you mean you have developed a closed form for it? If so, calculating the moment generating function would be the best (most precise) way. It's not too hard to calculate assuming the pdf isn't some beast of a function - it's an integral of the pdf exponentiated. Post it here, i'm sure a few people would have a go. If you have an empirical distribution rather than the closed form there are estimators for skew/kurtosis - something like R should have a function, or at least a package, to do this. If you have a closed form and really don't fancy the integral you could build an empirical distribution by taking samples from your distribution and then use an estimator for skew/kurtosis. Should converge to the true values for a sufficient number of samples, assuming the estimators aren't biased.
  12. How to calculate the Moments of a new PDF

    Do you know about moment generating functions?
  13. More than half your body is not human

    This paper explores some of the mood-changing organisms, might be a good place to start.
  14. More than half your body is not human

    Yep. Except you could divide sci-fi authors into two camps: those who actually try to extrapolate the future based on current scientific progress and those who just want to tell a story within the context of some future, fanciful or otherwise. But in an attempt to keep this on-topic i'd be interested to know about any sci-fi stories which utilise the microbiome. Maybe plants influencing humans by introducing some organisms into the human gut flora.
  15. More than half your body is not human

    And everyone forgets all the sci-fi that unsuccessfully predicted the future: aka most sci-fi.