How to verify a random number generator is truly random

[russ_watters]

Before I chose my answer, I looked at the poll results, then chose the number that had the most votes at the time...

 

[jobyts]

Doesn't quantum cryptography use pure random numbers (based on HUP)?

 

[Borek]

Before I chose my answer, I looked at the poll results, then chose the number that had the most votes at the time...

I did quite the opposite.

 

[Chi Meson]

Yeah baby! My random number's winning! Woo hoo! Way to go, yeah!

 

[BobG]

I'm kind of disappointed in my random number. I kind of like monogamous relationships with my numbers.

 

[LowlyPion]

I'm kind of disappointed in my random number. I kind of like monogamous relationships with my numbers.

It was bound to happen.

 

[Redbelly98]

Hey, wait, why are we obsessing about how we choose the number? As I interpret the poll instructions, "choose a random number", the OP has provided a list of random numbers that we are to choose from in any manner we see fit.

Now if the instructions had said "Randomly choose from the following list of numbers", that would be a different story.



p.s. in all seriousness, I have picked 7 using Excel's random number generator.

 

[Office_Shredder]

Hey, wait, why are we obsessing about how we choose the number? As I interpret the poll instructions, "choose a random number", the OP has provided a list of random numbers that we are to choose from in any manner we see fit.

Ooh, nice catch. The ambiguity here could destroy the integrity of the results. We'll have to create an independent commission to investigate further

 

[LowlyPion]

Ooh, nice catch. The ambiguity here could destroy the integrity of the results. We'll have to create an independent commission to investigate further

We'll need a Random Number Czar then to mediate.

 

[Moonbear]

Hey, wait, why are we obsessing about how we choose the number? As I interpret the poll instructions, "choose a random number", the OP has provided a list of random numbers that we are to choose from in any manner we see fit.

Now if the instructions had said "Randomly choose from the following list of numbers", that would be a different story.



p.s. in all seriousness, I have picked 7 using Excel's random number generator.

Ooh, nice catch. The ambiguity here could destroy the integrity of the results. We'll have to create an independent commission to investigate further

We'll need a Random Number Czar then to mediate.

This is why I love PF and the people here so much.

Wow, there's a cluster of mentors all in the middle. Integral is the only mentor who broke away from the pack. Contributors seem to be more independent thinkers, with numbers chosen throughout the range.

 

[EnumaElish]

How about this for a fair random process?

You grab a handful of sand. You then count how many grains of sand there are. Take the number and the remainder after dividing it by 20 should not be biased.

Here's my reasoning: the bounds aren't fixed on how many grains there can be. This means that there is no inherent bias in the range of values. You will usually get many more than 20 grains of sand, so the part that's actually deciding the outcome is sufficiently masked.

Are there problems with that?

Is "fine granular stuff from a burst stress ball" an acceptable substitute for sand?

 

[AUMathTutor]

As long as you don't use all of it... maybe?

 

[flatmaster]

My probability is a little rusty. What sort of discrete probability distribution would theoretically be expected here considering it was truly random? Poisson Distribution? A Bayesian analysis could tell us the probability that this data is actually a random distribution. Might do that later.

 

[qntty]

My probability is a little rusty. What sort of discrete probability distribution would theoretically be expected here considering it was truly random? Poisson Distribution? A Bayesian analysis could tell us the probability that this data is actually a random distribution. Might do that later.

If it was truly random, a uniform distribution would be expected, would it not?

 

[flatmaster]

If it was truly random, a uniform distribution would be expected, would it not?

For a sufficently large number of votes, it obviously would. However, for a small number of votes, there are outliers. Consider the first vote as your only data. A frequentist prospective would say that a random number between 1 and 20 is defined as that number.

 

[DaveC426913]

Is "fine granular stuff from a burst stress ball" an acceptable substitute for sand?

 

[colonelcrayon]

my @numb = (1 .. 20);

my $num = int(rand(19));
print @numb[$num];

Perl does it for me. I got 9.

EDIT: This is what I get for approaching a simple problem with a solution already in my mind. It might make more sense to just print $num and ditch the array... :P

 

[Moonbear]

So, how do you know a number is generated randomly? Wouldn't even a so-called random number generator need to have some sort of rules to generate the numbers?

 

[jobyts]

So, how do you know a number is generated randomly? Wouldn't even a so-called random number generator need to have some sort of rules to generate the numbers?

A computer cannot generate pure random number. What computer generates is a pseudo random number. For most of the random number applications, pseudo random numbers are more suited than pure random numbers. Pure random numbers have very little applications.

 

[DaveC426913]

A computer cannot generate pure random number. What computer generates is a pseudo random number. For most of the random number applications, pseudo random numbers are more suited than pure random numbers. Pure random numbers have very little applications.

You can start with a seed rather than using a system-generated randomizer.

 

[Moonbear]

A computer cannot generate pure random number. What computer generates is a pseudo random number. For most of the random number applications, pseudo random numbers are more suited than pure random numbers. Pure random numbers have very little applications.

So, still, how would you know if a number WAS a pure random number? Where do they come from and how would you recognize them?

 

[siddharth]

So, still, how would you know if a number WAS a pure random number? Where do they come from and how would you recognize them?

Maybe using a natural process which is random, like the decay of an atom. If there's geiger counter connected to a computer, and tracks the delay between individual decays.

There are also tests for randomness which may give a pretty good idea of how random a sequence of numbers generated by a pseudo-random number generator are (although, these can easily fail). In fact, in my senior thesis, I have to perform a lattice monte-carlo simulation, and the pseudo-random number generator I use has a period of 2¹⁹⁹³⁷-1

 

[BobG]

My probability is a little rusty. What sort of discrete probability distribution would theoretically be expected here considering it was truly random? Poisson Distribution? A Bayesian analysis could tell us the probability that this data is actually a random distribution. Might do that later.

If it was truly random, you'd expect a uniform distribution.

If you ask humans to pick a random number from 1 to 20, you'd expect a spike at 17. 37 is an even more popular random number than 17 if the range is 1 to 100. The favorite random number from 1 to 10 is 7.

The question was asked to a non-typical audience. Some of the responders seem more proud of how they picked their random number than they are of the number they picked.

 

[CRGreathouse]

We have 87 responses so far, and the chi-square value, 94.63, is below the 95% threshold of 108.65.

We're still random!

 

[Redbelly98]

2 seems rather unpopular in this poll so far (1 out of 88 responses, 1.1%)