Questions about the statistical process of sampling from a population, in order to obtain information for use in statistical learning, estimation, hypothesis testing about some population or process. Use this tag along with the tags (probability), (probability-theory) or (statistics).
Questions tagged [sampling]
1377 questions
2
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Joint Distribution and Sampling Distribution
There are three different incomes, x, and their proportions, f (x).
$ 10,000 0.40
$ 30,000 0.40
$ 50,000 0.20
How do I calculate the joint distribution for X1 and X2, which are a random sample of two incomes?
I'm new to this, so any help is…
Rosie E
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- 8
2
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1 answer
decimation in signal processing
Recently I was struck with the following question:
And this is what I think about it:
"Downsampling is one of the rare processes that are NOT time invariant. From the very nature of it's operation, we know if we delay the input sequence by one…
user146324
2
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1 answer
Approaching a desired but infeasible distribution when constructing a sample
Suppose you have $N$ balls in $C$ different colors, and a "desired" distribution of those $C$ colors (eg 20% red, 80% blue). Your task is to build a sample (not really a random sample per se) of $S$ balls, with colors distributed "as close as…
TCC
- 123
2
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2 answers
What is Rejection Sampling?
I just start to learn this topic and I don't understand what rejection sampling is. can someone give a brief explanation about it? I need to do rejection sampling in R programming.
Mia
- 23
2
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1 answer
How to calculate error margin on measured number of occurd events when sampling
We are measuring the number of times a certain event happens. We do this with the help of sampling, so that we only report events with a probability p. For example p=0.01 would result in about 1/100 events coming through. Now, if we have measured N…
Frans Ekman
- 21
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0 answers
How can I generate samples from some correlated exponentially distributed random variables?
I want to generate some samples from a set of correlated exponentially distributed random variables. I have the correlation matrix between these random variables.
For multivariate normal distributions, one can easily use Cholesky/Eigenvalue…
Vahidn
- 205
1
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0 answers
Design effect due to survey weights
I have a quick question on design effects due to survey weights. I would like to ask help since I am stuck in some particular parts though. Here it is:
Show that the following expressions for design effect due to weights are equivalent:…
1
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3 answers
While describing sampling theorem, is it $f_s \ge 2 f_m$ or $f_s > 2 f_m$?
I have a doubt regarding sampling theorem.
Sampling theorem states that if a band limited signal has to be recovered after sampling, then the sampling frequency $f_s$ should obey $f_s \ge 2 f_m$ where $f_m$ is the maximum frequency content in the…
dexterdev
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0 answers
Statistical Sampling for Tasks With Different Complexities
We have contractors submitting tasks of different complexities (High/Medium/Low) and we would like to audit them. Considering the auditing resource availability, we have to sample the submitted tasks and perform auditing.
I am planning to adopt "ISO…
Math Lover
- 11
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How to do structured random sampling?
I'm not sure the title is the best fit but I'm not sure how else to put it without a paragraph worth of describing what I want to do:
Imagine you have an image of some set resolution, say, 1024x1024, with three color channels an eight bits worth of…
kram1032
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Simple counterexample to sampling theorem
I know this has to be wrong, but can't see what is wrong with it:
Take a simple sinusoid. It crosses zero every half cycle. Sample it at double its frequency. If the samples coincide with the zero-crossings, you get all samples at zero. In that…
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Purpose of sampling when we already know the exact PDF formula of the distribution
Mabybe this question is duplicate of my other question here : Is PDF always given when we do sampling?
So what I've learned is that, when we already know the exact formula of PDF, we can calcuate any statistics that we want to know.
But I also know…
Young Hyun Yoo
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0 answers
How to sample uniformly from sets with elements from two classes.
I need help defining a sampling procedure.
Here is problem the set up:
I have a population consisting of 50 sets of different sizes. Each set contains instances belonging to one of two classes: $C_1$ or $C_2$. Note that each set contains elements…
bleb
- 11
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It is known that IQ scores have a normal distribution with a mean of 100 and a standard deviation of 15
a) a sample of 36 students is selected. What's the probability that the sample mean IQ score of these 36 students is between $95$ and $110$?
b) same as a but what if the sample size is $100$ instead?
My work:
X~N(100, 225)
$\sigma = 15$
$\mu =…
user833797
1
vote
0 answers
Why is the dynamically weighted importance sampling(IS) biased?
I have read the original paper of dynamically weighted IS. However, I do not understand why is the ordinary IS is unbiased, but the dynamically weighted IS is biased.
From the paper, it can be proven that the expectation of importance sampling is…
HZ-VUW
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