The randomness tag has no wiki summary.
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34 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 ...
-1
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0answers
31 views
Is my One Tail Hypothesis correct?
Testing the sale of marijuana in Colorado and Washington before and after legalization. The numbers are made up and random.
...
0
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0answers
42 views
Determining sample size in a non-normaly distributed data
I want to take some samples from a database nearly ~150.000 records of a non-normally distributed values. From this link I obtained some common procedures to find a sample, influenced by The level of ...
2
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2answers
60 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
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1answer
43 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
50 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?
...
2
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1answer
75 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
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0answers
38 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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0answers
48 views
ascertaining the randomness of a list of numbers [closed]
Assume that I have a series of DNA mutations occurring at specific positions x= [2, 3, 10, 14, 20] drawn from a sequence of length 50.( has positions 1 to 50) How ...
4
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2answers
109 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
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1answer
96 views
21
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2answers
447 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
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0answers
58 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
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2answers
52 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
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0answers
56 views
Stock price max / min strangeness
Stock markets are often described as following a random-walk or something similar. I have a process that automatically picks a trade entry time and a trade exit time for a given stock. After 1000 ...
0
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0answers
16 views
Estimating the randomness of an SRS
I have noticed that normal population parameters can be estimated accurately with a reasonably small sample.
It occurs to me that this is only possible because of the assumption that the random ...
0
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1answer
54 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
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1answer
116 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
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0answers
174 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 ...
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0answers
93 views
measuring randomness using runs test [closed]
I try to measure the randomness of data using the runs test (beside the chi square test). I get following values for a file produced by /dev/urandom:
...
1
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2answers
149 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 ...
5
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3answers
157 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
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2answers
174 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
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3answers
388 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 ...
0
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1answer
688 views
Ljung-Box test: Basic Questions
I'm interested into the Portmanteau tests for fitting ARIMA models and ended up to Ljung-Box test and their implementations for R-statistics. I've read already some relative question on the subject ...
4
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2answers
124 views
Can one force randomness in a sample?
I recently spoke to a large qualitative analysis company who were working on in-depth analysis of the potential customers of train company. I asked them how they chose the people to include in their ...
3
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1answer
120 views
Is there a Bayesian equivalent to a Wald-Wolfowitz runs test?
I have a sequence of observations and I would like to determine if the observations in the sequence are mutually independent. Wald-Wolfowitz is a non-parametric test that can be used to check for ...
6
votes
1answer
98 views
How to sample randomly from a population?
What do you think about the following method to perform a random sampling:
Generate as many floats (between 0 and 1) as individuals using a quantum random generator (each value appears only one ...
13
votes
2answers
260 views
Random walk with momentum
Consider an integer random walk starting at 0 with the following conditions:
The first step is plus or minus 1, with equal probability.
Every future step is: 60% likely to be in the same direction ...
24
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6answers
746 views
Why is it bad to teach students that p-values are the probability that findings are due to chance?
Can someone please offer a nice succinct explanation why it is not a good idea to teach students that a p-value is the prob(their findings are due to [random] chance). My understanding is that a ...
2
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0answers
61 views
Best way to find non-randomness regions in these or similar count data?
Let say I have data in a shape:
[0,0,0,0,1,0,0,0,1,1,0,0,0,0,0,0,0,0,1,0,0,2,0,0,0,....] - so mainly zeros....
However I know how long is my 'signal' and how many counts are they.
Is it possible ...
-1
votes
1answer
210 views
Is there self-similarity in true randomness? [closed]
Would a truly random function exhibit self-similarity?
By truly random I basically mean that if you have some function that produces a binary value, each new value will have exactly 50% chance of ...
10
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3answers
2k views
Can non-random samples be analyzed using standard statistical tests?
Many clinical studies are based on non-random samples. However, most standard tests (e.g. t-tests, ANOVA, linear regression, logistic regression) are based on the assumption that samples contain ...
2
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2answers
323 views
How to find out if a set of daily measurements are random or not?
There is a set of daily measurements. Time and measured values are both discrete. I want to find out whether measured values depend on the day the measurement was taken, or whether measurements are ...
2
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3answers
303 views
Long tailed distributions for generating random numbers with parameters to control tail heaviness
I have to generate random numbers for my algorithm based on probability distributions. I want a distribution which has heavy tails and is unskewed, which can produce numbers far away from location ...
3
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1answer
58 views
How can I even out a random distribution while minimising how far each data point is moved?
I have a software application which uses a queue and multiple processors to process those jobs. Jobs get re-run on a daily basis for customers, but we also have new customers signing up regularly.
...
11
votes
1answer
509 views
Scrambling and correlation in low discrepancy sequences (Halton/Sobol)
I am currently working on a project where I generate random values using low discrepancy / quasi-random point sets, such as Halton and Sobol point sets. These are essentially $d$-dimensional vectors ...
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2answers
145 views
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:
...
14
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4answers
617 views
What is wrong with this “naive” shuffling algorithm?
This is a follow-up to a Stackoverflow question about shuffling an array randomly.
There are established algorithms (such as the Knuth-Fisher-Yates Shuffle) that one should use to shuffle an array, ...
7
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0answers
419 views
Testing (and proving) the randomness of numbers [duplicate]
Possible Duplicate:
Testing random variate generation algorithms
What's a good way to test a series of numbers to see if they're random (or at least psuedo-random)? Is there a good ...
