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.

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111 views

Finding the minimum sample size of an opinion poll

I have encountered the following problem in a textbook,: Assume that 28 % of voters favored party A at some point. A later opinion poll gave a result of 30 % of voters favoring party A. What is ...
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2answers
75 views

Understanding Sufficient statistic.

A sufficient statistic for a parameter is a statistic that captures all the information about a given parameter contained in the sample. My question: Is the above sentence correct. (I think it is). ...
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21 views

Checking whether the given statistic is sufficient

A random sample is drawn from a Bernoulli distribution with $X_i = 1 $ with unknown probability $p$ and zero otherwise. Examine whether the following statistics are sufficient for the parameter $p$ ? ...
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14 views

Random assignments with 95% confidence of at least $K$ duplicate assignments

I'm running an experiment online. Of my $N$ test questions, each participant sees $M$ (randomly selected, $M < N$). If I want a minimum of $K$ responses to each question, how can I calculate a ...
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27 views

Help Determining a Statistically Significant Sample Size

I am planning on conducting an advertisement test for a website. Basically, I want to know whether visitors to my website would simply just return and convert regardless of seeing an ad or not. I will ...
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18 views

Importance Sampling Distribution

I have an infinite set of events and these event are either ture or false. I perform a monte carlo simulations to find the probability of an event being true. Now I have the knowledge that $A$ % of ...
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1answer
34 views

Resampling Probability

I've had a student working on some resampling problems. Here's a question I've posed to her: M consecutive draws of size K are taken from an urn with N balls. Balls are replaced between draws. ...
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7 views

Why is importance sampling always framed as calculating E(h(x))?

In all of the tutorials I've seen, importance sampling is always framed as a way to calculate: $$E(h(x)) = \int h(x) f(x) dx \qquad x \sim f$$ I don't understand why it is not framed as a more ...
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8 views

Statistics sampling on over-lapping categories.

I got a finite population. (e.g. a pool of files) The objective of the audit is to determine whether the files are in order. I need to audit the files for 5 different category on the population. Each ...
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455 views

Sampling Distributions

Parts being manufactured at a plant are supposed to weigh 40 grams. Suppose the distribution of weights has a Normal distribution with mean 40 grams and standard deviation 2 grams. Quality control ...
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1answer
58 views

Sampling demonstration using combinatorics

Suppose that I have a finite population of A's and B's, with properties: Population size: $n$ There are $n_1$ A's and $n - n_1$ B's (so that $p = \frac{n_1}{n}$, $q = \frac{n - n_1}{n}$) I'm ...
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1answer
15 views

hypergeometric distribution and random sampling

Is there any simple and fast algorithm (to be implemented in Javascript) to obtain a sample from the hypergeometric distribution? My needed sample size is very large (100,000,000).
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73 views

Chance to pick n balls out of N numbered ones where one ball is a specific number (without replacement, order doesn't matter)

An urn contains 120 balls numbered 1 to 120. Find the probability of choosing 3 balls without replacement that includes one ball numbered “11”. My attempt: Picking "11" would have the probability ...
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2answers
57 views

Basic sampling of joint random variables

If random variables $X \in \mathcal X$ and $Y \in \mathcal Y$ are sampled jointly from a target distribution $\pi$, i.e. $(X, Y) \sim \pi(x, y)$, is $X$ sampled from the correct marginal? In other ...
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85 views

Monte Carlo sampling and Kolmogorov–Smirnov test in practice

I have two deterministic algorithms, Algorithm 1 and Algorithm 2. The first has $m$ inputs and one output, and the second has $n$ inputs and one output. The distributions of the inputs of the ...
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26 views

Sampling into two sets

Let $N$ be the set of integers $1,\cdots,n$ and let $A$ be a set of numbers sampled independently from $N$ such that each element of $N$ has probability $p=0.5$ to be selected. I am trying to answer ...
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23 views

How can I tell whether sample size is inadequate or not ?

I am given sample size of 15322 students and our research topic is to find out a relationship between students academic performance and participation in sports team. The question asks " do you think ...
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39 views

oversampling by 2, which method is correct?

I want to oversample a continuous-time signal by a factor of 2. My signal is: $ r(t_1, t_2) = \sum_i \sum_j a_{i,j} h(t_1 - iT, t_2-jT)$, where $a_{i,j} \in {\pm 1}$ and $h(t_1,t_2)$ is the kernel ...
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2answers
21 views

Can we predict next sample using the existing samples?

Suppose that I have 18 data points and I'm sampling 3 data points each time. Suppose that I have 60 samples (each has 3 data points). Can we predict the next sample (of 3 points) from the existing ...
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91 views

Importance Sampling of 2D constant piecewise function convertible to 1D?

So I have a constant piecewise 2D function (luminance values of pixels of an image) that I am writing an importance sampling algorithm for. I was going to write my algorithm by first sampling the 1D ...
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44 views

Urn with marbles, unknown number of colors

When I started with this calculation I thought this was going to be a flashback from school decades ago but now after searching I'm confused if I'm over thinking it or if it's not as trivial as I ...
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2answers
18 views

metrics for density-sampling similarity, beyond likelihood

I am looking for a metric that would evaluate the distance between a sample $S$ and a density function $D$ Building a sample from a known distribution can be done using a monte-carlo sampling, ...
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157 views

Nyquist–Shannon Sampling Theorem Counter Example?

I was learning about the Nyquist theorem regards signal processing the area of interest which I will rephrase below: Given a signal lasting infinitely long with a maximum frequency of f, then you can ...
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39 views

probability integral transformation and distribution of P= P[ |T| <= |t|] .

The task is to find the distribution of P. where , P=P[ |T| <= |t|]. (T is a continuous random variable with PDF f(t)). now , I tried to make the following two arguments : 1.P= P[ |T| <= |t|] ...
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12 views

central limit theorem and sampling dist.

If you takes samples from a distribution, and you can see that they have different variances, can the central limit theorem still be applied. The computer vision teqnique i am referring to is this ...
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1answer
37 views

Is there any known method to fit plane onto sampling data?

For example I have the variables x, y (or higher dimensional data in general) and a probability density distribution p(x,y). I want to approximate p(x,y) as a linear function, a plane in this case, at ...
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1answer
300 views

Example of a real-world situation where multivariate analysis is applicable.

I have searched a lot of site to understand the situation where multivariate analysis is applicable. But not got any easily understandable example. Would you please give me a real-world example where ...
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1answer
26 views

How to Calculate Population from A given Set Of Sampels

I have a sample set of data collected using a SRS of books with IDs from 1 to 100. {90,60,6,39,46,26,16} Using this data how can I estimate the max, in this senario I know the max id, but what if I ...
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1answer
65 views

Efficient method for finding the number of combinations of values so that the sum is a certain number

I know one can make a sample space for this problem, but are there any other ways of solving a problem like this: Each letter has a number value. Find all possible combinations of the letters that ...
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1answer
70 views

Estimate the number of trials needed to observe all the possible outcomes of an experiment [duplicate]

I am stuck with the following problem: Each package of Pokemon cards contains 1 of N possible legendary Pokemon. How many packs do you expect to buy to get all N? We assume all N legendary cards are ...
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18 views

Doubt about the degree of freedom on standard error

Once I learn that the sample variance should be $s^{2}=\sum(X_{i}-\mu)^{2}/(N-1)$, I was told that "N-1" is came from the degree of freedom, even I didn't understand well the reason. Now, I am doubt ...
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1answer
19 views

A question about importance sample and Metropolis Algorithm

I am reading this paper by Beichl, I., & Sullivan, F. (2000) on Metropolis algorithm. I understand rejection sample. In the section "The Rejection Sample", I can understand the equation: ...
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108 views

Sampling via SRSWOR and biasedness of estimates

In a survey to estimate the proportion "p" of votes that a party will poll in an election, the voter list is divided into male and female lists. A sample of 100 from each list by simple random ...
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25 views

Approximation of a circle arc based on two lines, is this correct? How to rotate it afterwards?

Intro: We have two wheels that are rotated by something called T. I can tell T to rotate both wheels so much that they roll forward d cm (as shown in box A on the picture). I also have to keep track ...
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30 views

$100(1-\alpha)$% confidence interval

$100(1-\alpha)$% confidence interval for population mean $\bar Y$ $$\bar y\pm Z_{\frac{\alpha}{2}}\sqrt{\mathbb v(\bar y)}$$ Why is this $Z$ value depending on $\alpha$ important for constructing ...
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13 views

this undersample example doesn't make sense

I am studying for my DSP final and something doesn't make sense to me. If I have a continuous time signal $sin(12*pi*t)$ being sampled at T=0.1 sec. I get aliasing because I undersampled. I get ...
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23 views

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 ...
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29 views

Fourier Transform of a function with sinusoidal sampling

What is the relation between the Fourier Transform (FT) of $f(x)$ with regular sampling and the FT of $f(x)$ with sinusoidal sampling? In other words, it's a FT of a function composition $f\circ ...
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1answer
26 views

What happens to fourier transform of the sampled output of pure sinusoidal input of 26kHz if sampled with 44.1kHz sample frequency?

Because pure sinusoidal signal only contains impulses, I was wondering what happens to the fourier transform of the sample output from the sinusoidal input of $26$kHz if the sampling is done with ...
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1answer
40 views

Chebyshev Application [closed]

If we have a sample mean of $\overline{X} = (X_1 + X_2+\ldots+ X_n)/n$ and mean $m$ and standard deviation $s$, how large should the sample size $n$ be so that with probability $.99$ the error ...
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1answer
46 views

Infinite samples from uncountable sample space

I'm drawing one single sample from an uncountable sample space. I know the probability of sampling any given single point is zero. Now, what if I draw samples again and again and again, to infinity? ...
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21 views

Reservoir sampling from a stream containing duplicate items

Given an infinite stream with duplicate items, say, $S=\{1,2,2,1,3,2,\ldots\}$. How to uniformly sample $k$ items from its non-duplicate version, i.e., $S'=\{1,2,3,\ldots\}$? I known there is a ...
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1answer
30 views

Multivariate sampling of $F(x_1,…,x_n)$?

Let $$(X_1,...,X_n)\sim F(x_1,...,x_n)$$ (not independent). How can I sample from this distribution? In the univariate case, on can use $F^{-1}(u),u\sim U(0,1)$. However, in the multivariate case ...
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32 views

Simulate from a distribution using Metropolis-Hastings and Rejection Sampling?

We have covered the basics behind rejection sampling as well as Metropolis-Hastings from class, but I am not sure how to use the two in conjunction to solve the following problem: Given $\pi(x) = ...
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1answer
28 views

How can I uniformly draw points from an ellipsoid?

Specifically, given a positive definite matrix $A \in \mathbb{R}^{n \times n}$, how can I efficiently generate points $x \in \mathbb{R}^n$ that satisfy $x^TAx \leq 1$? I know how to do this when the ...
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3answers
79 views

Sampling Distribution; Statistics. Please verify my answer

Professor earns average $ \text{\$} 65,500$ per year with standard deviation of $\text{\$}3,500$. Random sample of $64$. a. Describe sampling distribution of sample mean $\bar{x}$ of average ...
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24 views

Sampling Distribution of the Mean

I want to know if my reasoning is correct. Let's say I got two normal distributed variables: Variable "X": 5.4 (mean), 2.856 (variance) Variable "Y": 5.4 (mean), 5.062 (variance) Let's pick 16 ...
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1answer
42 views

Bivariate sampling for distribution expressed in Sklar's copula theorem?

In the univariate case, one can easily sample a distribution via random numbers $u\sim[0,1]$ and plugging into $F^{-1}(u)$. I have a bivariate distribution constructed via Sklar's theorem on Copulas: ...
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23 views

recovering bits from distorted signal

I have a signal: $r(t) = \sum_k a_k g( lT/2 -k(T+\Delta T) )$ where $a_k \in \lbrace\pm 1\rbrace$, $g(t)=\frac {\sin(2\pi t/T)}{2\pi t/T}$, $T/2$ is the sampling period, and $\Delta T$ is a ...
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28 views

Sampling combinations (from a binomial coefficient) without replacement

The total number of combinations of $k$ items out of $n$ total is $n \choose k$, or a binomial coefficient. This can be a very large number even for pretty small $n$. The binomial coefficient ...