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In common parlance, randomness is the apparent or actual lack of pattern or predictability in events. A random sequence of events, symbols or steps often has no order and does not follow an intelligible pattern or combination. Individual random events are, by definition, unpredictable, but if the probability distribution is known, the frequency of different outcomes over repeated events (or "trials") is predictable. For example, when throwing two dice, the outcome of any particular roll is unpredictable, but a sum of 7 will tend to occur twice as often as 4. In this view, randomness is not haphazardness; it is a measure of uncertainty of an outcome. Randomness applies to concepts of chance, probability, and information entropy.
The fields of mathematics, probability, and statistics use formal definitions of randomness. In statistics, a random variable is an assignment of a numerical value to each possible outcome of an event space. This association facilitates the identification and the calculation of probabilities of the events. Random variables can appear in random sequences. A random process is a sequence of random variables whose outcomes do not follow a deterministic pattern, but follow an evolution described by probability distributions. These and other constructs are extremely useful in probability theory and the various applications of randomness.
Randomness is most often used in statistics to signify well-defined statistical properties. Monte Carlo methods, which rely on random input (such as from random number generators or pseudorandom number generators), are important techniques in science, particularly in the field of computational science. By analogy, quasi-Monte Carlo methods use quasi-random number generators.
Random selection, when narrowly associated with a simple random sample, is a method of selecting items (often called units) from a population where the probability of choosing a specific item is the proportion of those items in the population. For example, with a bowl containing just 10 red marbles and 90 blue marbles, a random selection mechanism would choose a red marble with probability 1/10. Note that a random selection mechanism that selected 10 marbles from this bowl would not necessarily result in 1 red and 9 blue. In situations where a population consists of items that are distinguishable, a random selection mechanism requires equal probabilities for any item to be chosen. That is, if the selection process is such that each member of a population, say research subjects, has the same probability of being chosen, then we can say the selection process is random.According to Ramsey theory, pure randomness is impossible, especially for large structures. Mathematician Theodore Motzkin suggested that "while disorder is more probable in general, complete disorder is impossible". Misunderstanding this can lead to numerous conspiracy theories. Cristian S. Calude stated that "given the impossibility of true randomness, the effort is directed towards studying degrees of randomness". It can be proven that there is infinite hierarchy (in terms of quality or strength) of forms of randomness.

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  1. S

    Mira Combiflow random cold water

    I’m after some advice. I’ve inherited my parents house. In the process of doing it up. My dad got a Mira combiflow installed about 15 years ago. Over the last couple of months every so often when it’s turned on the water runs ice cold even if I turn the handle to hottest temp. All other taps...
  2. fango7

    Random push fit pipe

    Random push fit pipe with no end on near toilet ,would this be leading to anywhere shower etc think it is connected to a longer pipe headed toward shower cubicle , seems very loose when i move it ,would it be leading to shower or just lying loose from a previous connection? Before new bathroom...
  3. D

    UFH zones come on at random - strange or normal?

    Hi. This UFH system is in my mil's bungalow purchased earlier this year. It has 9 zones, is run from a WB 37CDi combi, and uses Wavin actuators with a wall stat in each zoned room. It all appears to work just as it should. A few weeks back, tho', one of the two bedrooms warmed up excessively...
  4. F

    Random occurrences of no hot water

    Hi all, I posted a few months ago about a 'no hot water' problem, and it turned out that it was a diverter valve problem. But still, from time to time, not too frequently fortunately, we have only lukewarm/cold water in our taps/showers. What could be the problem? - sometimes, the trick to...
  5. G

    ATAG one random call up

    Hello I have an ATAG boiler controlled by an ATAG 1 thermostat been good for three years but now randomly called for heating on full temp ,not good with the current price of gas anyone got any ideas what’s causing this ? Cheers
  6. uksoundz

    Random USA to UK question

    Hi, I'm wanting to build something which isn't related to plumbing, however from the YouTube video I've watched (from the USA) has only USA parts from a store called Lowes. I'm wondering if any kind individuals could specify what the UK equivalent is here in the UK? Charlotte Pipe ¾ inch x...
  7. N

    Random noisy CH pipes when everything is off.

    I have an ideal logic 18 boiler in the utility room going to an unvented Tribune HE cylinder in the upstairs airing cupboard. I moved into the house as a new build just over 2 years ago. The heating and hot water are all working fine and the system pressure is within specs. About 6 months ago...
  8. Meady

    Random plumbing items for sale

    1 x Grundfos alpha 3 Circulator - £185 posted 1 x Merlyn Ionic Mb8 1500x1100 Bath Screen - £215 collected Multiple Honeywell Timer ST9100C programmers - £25 posted All items are brand new, the boxes from the timers may be a bit tatty but are in tact and everything is 100% complete. Cheers
  9. R

    Shower pump - random airlocks

    Hi forum, We have a >10 year old 2 Bar Aqualisa Type 1 pump for the shower. Recently it started acting up... Sometimes the cold would completely stop but the hot would keep flowing (almost scalded myself in the shower), when this happens the pump makes an intermittent stop/start revving sound...
  10. mrb1972

    Random bath plug hole smell and gurgling

    Hi, We moved into a new house a few months ago, we have a main bathroom (which is not used) it has a problem with the bath plug hole emitting a sewer/egg smell about every 7 days, running water down the plug hole clears the smell but only for about 7 days then it comes back again. Now a second...
  11. P

    Random rumbling noise on new Vaillant Ecotec Plus 615 VU

    Hi all. I've recently been getting regular complaints from customers about their new ecotec plus 615 vus regarding an intermittent loud rumbling noise. Checked high and low co2 ratios, gas inlet pressure etc but never find a cause? I've had Vaillant go back to a few but they dont give me any...
  12. Harvest Fields

    A random one for a Sunday evening.

    Does anyone know anything about electric boilers or electric combi boilers, if such a thing exists?
  13. R

    Random radiators stopped working after cold weather

    I have a Worcestor Danesmoor boiler that lives in a stone outhouse and heats the water and radiators in my house. The heating is set to come on at certain times of day, but during the recent cold weather it stopped coming on. I tried pressing the manual reset button a few times, but assume...
  14. D

    Overly complicated, random function, dangerous!

    Hi to all specialists and happy new year. I am looking for some advice re a situation that I cannot resolve. Over the last 5 years I have built a 3 storey house in Skovakia ( I am a Brit and my wife is Slovakian). I employed the local specialist to supply and install a quite complicated heating...
  15. K

    Random clanking from cold water pipes

    Hi, I'm hoping someone might be able to help me. At random times throughout the day there is a loud banging coming from what I believe are the the coldwater pipes. It's not a central heating issue as it was happening prior to our boiler being reconnected, and it's not to do with flushing the...
  16. M

    Worcester Heatslave Random lockout

    I have a Worcester Heatslave 20/25 with bentone b11c burner, The burner has started randomly locking out, it can run for 30 minutes or 10 hours before locking out, it always resets and fires straight away. I have cleaned the oil filter and checked the photocell which are all fine. I do a lot...
  17. Harvest Fields

    Random emails all this week

    Just thougt that I would ask. So I have never, ever, ever had an email from Victorian Plumbing. However I have now had 3 in the last week. Wondered if anybody else had noticed the same thing happening?
  18. S

    Vaillant Eco Boiler - Heating will keep coming on and off at random times!

    Radiators keep coming on and off, could just be a coincedence but I have noticed this happens on really cold days/nights. Frost protection? I have the Hot Water and Radiotor dial on the boiler turned to half way. Thermostat in house switched off or set to under the dispayed temp. On the odd...
  19. N

    Vaillant Boiler and Random Switch!! Help!!

    Hello, I have just bought a new house and there is a boiler and switch (photos attached) that I have no idea how to use!! i've been on YouTube, read the instructions and all that happens is the radiators warm up, get hot and then completely turn off but the flat still hasn't actually warmed up...
  20. T

    Central heating pump running at random times?

    Hi folks, i wonder if you could help me? My central heating system (about 4-5 year old worcester Greenstar condensing boiler with a honeywell controller and a grundfos pump) runs from about 06:00 until about 22:00 as per the timer. But over the past few weeks the pump has started running for...
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