The tag has no wiki summary.

learn more… | top users | synonyms

1
vote
1answer
32 views

Is it possible for two independent people to generate randomness?

It is well documented that people are not very good at generating random sequences. However, is it possible that two people, working independently, could generate randomness together? Consider the ...
0
votes
0answers
6 views

How many bags of Lego minifigs do I need to buy to complete a set? [duplicate]

Lego sells minifigs. They release these as "series". Series 11 has 16 different figures to collect. Each packet is sealed and opaque. You do not know which figure is in the pack when you buy it. ...
1
vote
1answer
35 views

Multilevel: Can I include two dummy variables of a 7-dummy-set into a random slope?

I am calculating a two-level linear multilevel analysis. A look at the random intercept random slope model showed me a significant decrease in my model deviance if I include two dummy variables. Those ...
1
vote
0answers
31 views

How can I model this problem?

Genetic algorithms are a kind of evolutive approach to problem solving where solutions are randomly generated and crossed with each other as to produce other solutions. With each generation or ...
0
votes
0answers
15 views

The outlier in non-random data

I have tested a time series data by using Run Test. The result shows that it is non random. How could I detect which data point(s) caused that non-randomness? Is there have any methods I can use? ...
0
votes
0answers
19 views

Testing for consistency in survey data

I have a panel of 6 persons which each have generated 2 recipes (cooking), R1 and R2. I have then asked everyone in the panel to ...
3
votes
0answers
62 views

What kinds of PRNG exist outside Linear congruential generators?

I'm kinda running out of words, Linear congruential generator are really low quality PRNG but it was all I needed for some basic stuff, now I need to fill the blank and get to know other families of ...
1
vote
4answers
64 views

Are integer results from random number generators unlikely?

If I generate a random float value between 0…1, say to 40 digits, or n digits, aren't the chances of getting a true zero (0) or a true one (1) incredibly small? On the zero condition, every 0–9 digit ...
2
votes
3answers
76 views

Check if a certain procedure is random or not

I am not a statistician, but I have a personal project and I need a help. I will simplify the project a lot to make it more clear and easier to understand. Then in base of your answers, I can fit it ...
0
votes
3answers
2k views

Is it a truly random sample?

Any hints on how to solve this problem? A sample of 400 items is taken from a normal population whose mean as well as variance is 4. If the sample mean is 4.5, can the sample be regarded as a ...
1
vote
2answers
68 views

Does randomness imply independence?

By looking at a lag plot, it seems that my dataset is random (no autocorrelation whatsoever). Should this be sufficient to infer independence of observations? As a matter of fact, I know that the ...
0
votes
0answers
25 views

How to test a Random Number generator in R? [duplicate]

I have a random number generator of U(0,1), I apply the ks test on x, which has 10000 random numbers in [0,1]: > ks.test(x,"punif") and obtain this result: ...
2
votes
0answers
78 views

Precision and recall of a random classifier

My understanding of precision and recall tells me that there is a tradeoff between these two measures: you can improve one at the cost of the other. However, when I think of a random classifier (on a ...
0
votes
0answers
31 views

Linear Mixed Model Construction Suggestion

I'm currently working on some data that requires me to use linear mixed model. Explanation of Data Experiment of Drugs on Mouse I have 3 drugs and 1 control Unbalanced number of mouse for each ...
0
votes
0answers
17 views

Assuming a raster image is a random vector

I am currently working in remote sensing. It is quite common to find that the beginning of the statistical descriptions of techniques used in satellite image processing begin with defining the initial ...
0
votes
1answer
18 views

I have a source of numbers. Is there a way to estimate the probability for the given number to originate from it?

The source in question is some blackbox which output looks completely random to me, yey I haven't tested if for randomness quality. I don't exactly know insides of blackbox but can easily caputure it ...
6
votes
1answer
182 views

Probability to draw a black ball in a set of black and white balls with mixed replacement conditions

When a black ball is drawn, it is not replaced in the set, but white balls are replaced. I have thought of this, with the notations: $b$, $w$ the initial number of black and white balls $x_i = (b ...
1
vote
1answer
44 views

Quality of randomness in generated random number

I have generated a list of 3 random number where each summed to 1. I would like to access the quality of randomness. What is the best mechanism to access this randomness? E.g my random numbers are. ...
0
votes
0answers
52 views

How to measure the randomness of a time series?

I have at least two time series. How can I measure which one of them is more random than the others? I am also interested in monitoring the changes in the amount of randomness over time for an ...
6
votes
2answers
296 views

How to generate random points in the volume of a sphere with uniform nearest neighbour distances

With respect to post (1) and post (2), I generated a large number of uniformly distributed points inside the ball of radius $R$ using $\frac{R_s U^{1/3}}{\sqrt{X_1^2 + X_2^2 + X_3^2}} (X_1, X_2, ...
1
vote
0answers
24 views

Modeling a list with a tunable degree of disorder/shuffling

Imagine we have a list of ordered numbers $L = (1, 2,\dots, N)$. I want to add an arbitrary amount of "disorder" to that list. For instance: Adding a little bit of disorder would permute a few ...
2
votes
0answers
73 views

What is the distribution of an outer product of random values mod P?

I haven't been able to answer this daunting question for days now and I am not able to find the right resource for it, so maybe someone here might help me out. Consider an outer product of two ...
1
vote
0answers
61 views

How to test the randomness of a sequence of real m-tuples?

1) Let $\{a_i\}_{i = 1, ...,n}$ be a real sequence generated by a pseudorandom number generator. How can I check the randomness of such real numbers using, for instance, Runs test? 2) Assume three ...
2
votes
1answer
232 views

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 ...
1
vote
1answer
344 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 ...
1
vote
0answers
42 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: ...
0
votes
1answer
461 views

Best way to test runs

I have the following sample: ...
0
votes
1answer
103 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 ...
3
votes
0answers
31 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. ...
2
votes
0answers
42 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 ...
2
votes
1answer
53 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 ...
0
votes
0answers
610 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 ...
4
votes
0answers
78 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 ...
2
votes
2answers
198 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 ...
1
vote
1answer
68 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 ...
1
vote
1answer
59 views

randomness and computers

How do computers achieve randomness if they really do ? How to decide whether something is random or not? Is there a measure of randomness? ...
7
votes
1answer
394 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 ...
3
votes
0answers
52 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 ...
4
votes
2answers
149 views

Randomly picking from $n$ choices roughly $n$ times. What's the resulting frequency distribution called?

Not sure of the best way of phrasing this question, but I'll give it a go. If I were to randomly choose whole numbers between 1 and $n$ a significant number of times relative to $n$ (say, $m$, where ...
0
votes
1answer
246 views

Why is the ROC curve of a random classifier the line $x=y$?

The title is my whole question.
24
votes
2answers
683 views

Are the digits of $\pi$ statistically random?

Suppose you observe the sequence: 7, 9, 0, 5, 5, 5, 4, 8, 0, 6, 9, 5, 3, 8, 7, 8, 5, 4, 0, 0, 6, 6, 4, 5 , 3, 3, 7, 5, 9, 8, 1, 8, 6, 2, 8, 4, 6, 4, 1, 9, 9, 0, 5, 2, 2, 0, 4, 5, 2, 8 ... What ...
2
votes
0answers
69 views

How can you select one of two individuals at random using a biased coin

Suppose you are given a biased coin for which the probability of getting a head is $p (0<p<1)$.Discuss how you will select one of two individuals at random using the biased coin.
1
vote
2answers
55 views

Co-occurance problem

I have a series of discrete, purportedly random whole numbers like this: v1 v2 v3 v4 v5 v6 42 23 10 07 01 35 05 02 26 25 49 18 35 18 43 29 26 28 36 59 26 15 34 35 I ...
0
votes
1answer
82 views

Test data for randomness with repetitions

I have an experiment where I am trying to determine whether the answering behavior of participants can be explained as random answering. I.e. every participants will have to answer multiple questions ...
2
votes
1answer
221 views

Runs Test and Chi Square Distribution

I want to identify random data by applying some tests to the observed byte stream. I used the chi square test already on a frequency analysis, which works fine. To reduce the false-positive rate I ...
2
votes
0answers
325 views

interpreting chi square value for validating random numbers

I am trying to use the chi-square test for identifying random data. I have 256 categories, i.e. 255 degrees of freedom and count the occurrence of byte-values (0-255). As suggested by Knuth, the ...
1
vote
2answers
224 views

When does a random test fail?

I must implement some Chi Square Test to test the randomness of "my" implementation, but I can't understand what this tests really say. The tests are different but what I always do is: divide in ...
6
votes
3answers
265 views

Test randomness of a generated password?

As you know, there are many password generators out there to increase computer security. Suppose I am given such a password (say, a string of letters, numbers, symbols, etc.), is there a way for me ...
0
votes
2answers
660 views

Probability of a randomly generated string being already present in a data set [duplicate]

Possible Duplicate: Simple combination/probability question based on string-length and possible-characters Suppose I have a collection of 1,000,000 unique strings where each string is ...
7
votes
3answers
874 views

What is the probability of n people from a list of m people being in a random selection of x people from a list of y people?

If I am selecting 232 people from a pool of 363 people without replacement what is the probability of 2 of a list of 12 specific people being in that selection? This is a random draw for an ultra ...