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
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sample distribution such that points are farthest apart
I need to plot some stuff and want to choose colors such that they are as distinct as possible.
Given a [0,1]^n cube how should one sample points without knowing beforehand the number of samples and at the same time the points are farthest apart on…
titus
- 123
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Clarification regarding sampling and reconstruction of $ f(t) = 2\cos(20 \pi t) + 3\cos(80 \pi t) + 4\cos(200 \pi t) $
The following signal
$$ f(t) = 2\cos(20 \pi t) + 3\cos(80 \pi t) + 4\cos(200 \pi t) $$
is sampled at a frequency $F_s = 100\text{ Hz}$, then it is reconstructed using an ideal lowpass filter (no frequency given).
I am asked to determine the signal…
Jafar Eldeni
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Optimal proposal density for acceptance rejection sampling
For some project I have been sampling from the Gamma distribution. I have been using the exponential distribution intensively. One method I have employed is the Acceptance rejection sampling, particularly for the pdf given $f(x) = 8{e^{ - 4x}}x…
Anonymous
- 297
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How to continue sampling after a conditional rejection?
I encountered the following (to me) weird problem while trying to do some simple sampling.
I have a system that generates random numbers. Let's for simplicity assume the numbers are 0, 1 and 2 with uniform probability.
I generated one sample and…
Jonathan
- 111
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What is the right way of calculating Minimum sample size for metrics difference?
I have a population of $1000$ elements. I need to take a sample $n$, and compare metrics before and after policy impact. What is the minimum sample size for $95%$ interval confidence?
Based on Cochran formula it looks to be $385$. But this looks a…
john
- 111
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2 answers
Given a set of addresses, pick a geographically even subset for sampling
There are a certain number of houses spread randomly across a city. We have addresses and GPS coordinates for each house.
How can we select a geographically representative, fixed-size sample out of the houses in the selection?
To illustrate with…
quantif
- 193
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sampling and normal distribution
The random variable x is normally distributed with mean 68 cm and sd 2.5 cm.What should be the size of the sample whose mean will not differ from the population mean by more than 1 cm with probability 0.95?[Given that area under standard normal…
user447447
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Finding the sampling distribution of the packets of assorted resistors
A store sells a large number of packets of resistors. They are packed in $3$ packet sizes: $10$,$20$ and $30$ resistors per packet and are sold int the ratio $1:3:2$ respectively. A random sample of $3$ packets is taken from the shelve.
(i) List the…
ys wong
- 2,017
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analogy between iid and sampling with replacement
Are iid samples and sampling with replacement analogous to each other?
iid - Independent and Identically Distributed RVs, means that each sample is independent of all others and all samples are drawn from the same distribution.
sampling with…
gokul_uf
- 113
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hemisphere sampling and vector flip
I am currently implementing a uniform sampling of a hemisphere.
Since my hemisphere is oriented around a specific vector N, whatever the sampling algorithm used (uniform/cosine weighted/stratified/...) I must either: 1) sample on the whole sphere…
user815129
- 113
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Sampling Without Replacement : Draw x Red before Drawing RGB
I am struggling to get my head around how to solve the following problem and can only find solutions to simpler versions
Consider a bag containing x Red, y Blue and z Green marbles
What is the probability that one will draw n Red marbles before…
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What is the importance of the inclusive range in Reservoir with Random Sort?
I am reading the Reservoir with Random Sort page on Wikipedia, and the algorithm says (copied):
/*
S is a stream of items to sample, R will contain the result
S.Current returns current item in stream
S.Next advances stream to next position
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antithetic sampling
I am reading a book on antithetic sampling.It is said that the idea of antithetic sampling can be applied when it is possible to find transformation of $X$ that leave its measure unchanged (for example, if $X$ is Gaussian, then $-X$ is Gaussian as…
Jackie
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Random sampling, need some help and guides
i was asked to do an assignment on examining the Body Mass index of students. I have to select at least 50 students from my school, and i was asked to describe how I ensure the randomness of the sample. Can anyone explain to me how can i ensure the…
Guestttt
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How to estimate amplitude of a sinusoid from two samples
Given a sinusoid $x(t)=A\cos(t+\theta)$, I can estimate the amplitude $A$ if I take two samples separated by $\frac{\pi}{2}$. If $X_1=x(0+\theta)$ and $X_2=x(\pi/2+\theta)$. Then, $A$ can be estimated from $X_1^2+X_2^2$.
However, I am taking…
