Can you tell the difference between actions based upon flipping a coin and those based upon blind guessing or simulating randomness? This short video examines the frequency stability property.
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Author asks, can you determine which light bulb switched by flipping coin and then says answer is YES, but I followed both light bulbs and cannot figure it out, can somebody answer this question thank you.
As mentioned, the forged one is the one with uneven frequency of different sequences (the top one) and a truly random is supposedly contains an equal number of different sequences, though it is difficult to believe..
you can make a truly random number generator if you had a dice with n side and each side has equal weight and equal chance of landing on a given face and land on a flat surface then you have a machine that reads the face facing up however it is impossible to make a dice that has equal sides and equal weight distribution because some sort of gravity is pushing the dice in unequal forces and perfectly flat surface is impossible because of gravity, nuclear forces, electromagnetism
Anyone else think this is a bad example? The switch moves up and down and only has 2 options ON and OFF if you turn the switch ON how are you supposed to turn it ON again? The only other option after turning it ON is to turn it OFF... therefore the pattern has to be ON-OFF-ON-OFF-ON-OFF...etc.
My teacher did this where he asked some people in the class to truly flip a coin and write what they got and others to make up random sequences. He guessed who did what correctly each time by seeing if there were sequences of 6 heads or 6 tails in a row and determined this to be actual coin flipping. Really fascinating stuff.
Fascinating. I wanted to test this so I wrote a quick c++ program to run the simulation. I seeded srand with the system time and used modulus 2 to get a fairly random 0 or 1. A set of if statements checked to see which octal sequence showed up and counted them. I set it all up in a for loop to repeat 80,000,000 times.
I ran the program several times and the highest standard deviation I got was 4142. The lowest was 41. Those are really low deviations for 80mil random octal groupings.
thanks for your answer, but here is something extra, how is this true in relationship with time? I mean if you count sequences from time zero to time finish this property can apply , because you can count all possible combinations, but what about if you only count sequences in one hour? or two hours, and the light switches are spaced 5 minutes apart. I am working on such a problem and I'm searching for a solution. Thanks
Okay. Back to the video instead of praising khan academy, I'm sure it just wants to know how people feel of the video. Phrases such as "omg this video portrays things soooooo much cooler!" are so cliche. Get to the point.
I completely agree with this video. I don't think truly random numbers are possible.
@kbponline It's because videos and graphics convey much more information than the text do, and you use both ur eyes and ears to process these information.That's why videos seem more "meaningful" thatn text.
@Theomacho so what's your point? If you can't predict it, it might as well be random. By the way, random variables can have a distribution that is non-uniform and there are ways to get very close to "perfectly" random.
@Kevill Random is a hypothetical concept. A construct of human imagination. I find it illogical. You're making a good point. A computer is like an unbiased mind and it can't be told to do something at random. It needs data. Just like every other event in the universe. Cause and effect.
the physical act (of using the body to flip a coin) is also programmed but is stable because it is a physical expression without any conscious mind envolved
the conscious mind is not stable and does not produce stability
not even by impersonating randomness
A similar presentation was made in a probability class at Berkeley, with a different twist on the numerical trends. If interested, see the Radiolab archives & search for their episode on stochasiticity...
So if you were able to have an empty mind and told it to perform such a
task at random.
Would it stick to the mathematical randomness, or would it still have a bias on some patterns despite the fact that there are no thoughts in it's mind about patterns and what is, or isn't random?
Wrong, not every sequence is equally likely to occur. Or to be more precise, in 3 flips of a coin, every combination of heads and tails is equally likely, but in a large amount of flips, the odds of getting a specific sequence of length 3 depends on the sequence.
Well, a sequence of all 1s is just as likely as any other sequence. Still when you are just looking at it as outcomes of 1s and 0s instead of the sequence, it seems it would be unlikely for the sequence to contain only 1s or 0s compared to the odds of having half of them being 1s and half being 0s. Which seems to contradict the statement about the sequence.
All of which makes the video much more interesting since it does not contradict the statement . The difference is just the perspective.
So it shows human nature is to favor certain patterns. Would a person who has seen this video be able to have a better chance at pretending to be random and thus not get caught ?
Example, in terms of trying to be random as a competition, you can play Rock, Paper, Scissors against an advanced Computer Algorithm. I have done very well against the computer by not thinking about what i'm gonna throw.
really cool---the soviets used to generate code sheets by typing random letters on a typewriter---but their typists were not really typing randomly, they often just alternated hands---if plain text is coded using a random, non-repeating key, it is impossible to break---but if the key is not random (or cycles), then longer texts are vulnerable to crypt-analysis---i would love to know how non-randomness and/or cycles can compromise a cypher-text---please ♥
"if we flip a coin 10x it is equally likely to come up all heads, all tails or any other sequence you can think off". I had to think about that a little bit, given that the only thing I remember about statistics is the coin toss homework, 50% heads, 50% tails. So the probability of getting any one pattern in a 10x sequence of coin tosses is 1:1024, right? or is it 1:1023?
Although foreigners may now invest in A-shares, there is a monthly 20 percent limit on repatriation of funds to foreign countries.
Performance of A-shares.
Since its inception in 1990, including a major reform in 2002, the index has seen great fluctuations. Overall, however, it has grown along with the Chinese economy. The years 2015 to 2016 were a particularly difficult period, with a 52-week performance of -21.55 percent as of July 20, 2016.
As China grows from an emerging market to an advanced economy, there is substantial demand for Chinese equity. Stock exchange regulators continue efforts to make A-shares more broadly available to foreign investors and have them recognized by the global investing community.
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Current Dividend Preference.
Participating Preferred Stock.
Convertible Preferred Stock.
Cumulative preferred stock includes a provision that requires the company to pay preferred shareholders all dividends, including those that were omitted in the past, before the common shareholders are able to receive their dividend payments.
Non-cumulative preferred stock does not issue any omitted or unpaid dividends. If the company chooses not to pay dividends in any given year, the shareholders of the non-cumulative preferred stock have no right or power to claim such forgone dividends at any time in the future.
Participating preferred stock provides its shareholders with the right to be paid dividends in an amount equal to the generally specified rate of preferred dividends, plus an additional dividend based on a predetermined condition. This additional dividend is typically designed to be paid out only if the amount of dividends received by common shareholders is greater than a predetermined per-share amount. If the company is liquidated, participating preferred shareholders may also have the right to be paid back the purchasing price of the stock as well as a pro-rata share of remaining proceeds received by common shareholders.
Significance to Investors.