# Questions tagged [randomness]

Randomness is the lack of pattern or predictability in events. Randomness is often modeled with probability distributions, but can also be generated by deterministic processes.

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### Wilcoxon signed rank test on anonymous sample

I carried out a test on a group of 100 people. The test contained 10 questions with 5-point Likert scale answers (1 = Strongly Agree, 5 = Strongly Disagree). After the test was conducted, the group ...
2k views

### NIST randomness test fails in random generated bits

I am using the NIST randomness test suite which checks whether a bit sequence is random over 15 different tests. I have problems in verifying if this suite works fine. The situation is that if I input,...
66 views

### Finding a sample to represent a known population

Entire Population: 30,000 Known properties of population: Age, gender, height, weight, Ideal representative sample size: ??? This is for a mailing list test group selection. Problem constraints: ...
5k views

### Best way to test runs

I have the following sample: ...
2k views

### How exactly does the R random number generator work? [closed]

When I generate a random number using the following procedure: set.seed(123) rnorm(1) I would like to know what exactly is happening in this case? Is R reading ...
41 views

### How to check if a data sequence is really random? [duplicate]

I wonder how can I test if a data sequence is really random? Of course I can randomly cut it into equal pieces, and check if the correlation coefficient between different pieces on average is zero. ...
87 views

### How to select model when different models are preferred with different seeds?

I am trying to apply the lasso or ridge regression to my data set for the feature selection, but different random seeds produce different models. What is a good or universal way to obtain the final ...
92 views

### Filtering random guessers from daily surveys

Assume we're polling or surveying people about their predictions regarding some future event. This survey is done every day, and the event they are asked to predict is the same every time. For example,...
3k views

### Easy-to-apply tests for randomness

I'm interested in testing a sequence of numbers for randomness. I've done some searching and come across die hard and die harder. However these tests seem to require some expertise to apply, or at ...
167 views

### Sanity check to determine if 'random' data on disk drive may have been tampered with

I've got some code that does a Dept of Defense secure erase of disks, and would like to know about a good sanity check to run after the fact. Bottom line, the last write phase of a secure erase of a ...
761 views

### Best process for randomly drawing an odd and an even number

I want to draw a random number from 1 to 100. If this number is even, I want to then draw a random number from the odd numbers between 1 and 100. If the first number is odd, I want to draw a random ...
136 views

### Detecting/analyzing non-random permutations of a random sequence

I am looking for theoretical results regarding how easy it is to detect alteration of a random sequence. The permutation I am most interested in is where a subsequence of the random numbers is sorted,...
93 views

### randomness and computers [closed]

How do computers achieve randomness if they really do ? How to decide whether something is random or not? Is there a measure of randomness?
2k views

### Differential Entropy

Differential entropy of Gaussian R.V. is $\log_2(\sigma \sqrt{2\pi e})$. This is dependent on $\sigma$, which is the standard deviation. If we normalize the random variable so that it has unit ...
128 views

### Relation between statistical randomness, uniform distribution and independence

In Monte Carlo simulation, we often consider how well a sequence of generated points are. If I am correct, one aspect is statistical randomness: A numeric sequence is said to be statistically ...
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### Is it possible to predict the likelihood of an order of random events?

Sorry if this is a n00b question, I'm just trying to wrap my head around the problem. I am trying to refute conventional wisdom here, so any help is greatly appreciated. And now for the question: ...