Creating samples from a well-specified population using a probabilistic method and/or producing random numbers from a specified distribution.

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How to calculate probability of a random sampling of a population

Let's say that I have a city for which I know the size in square miles and I want to know the probability of a random sample of individuals from that population living within a certain threshold of ...
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13 views

Sampling Distribution of Proportions [on hold]

If births of boys and girls are equally probable, find the probability that of the next 200 children born (i) less than 40% will be boys ans: 0.0024 (ii) between 43% and 57% will be boys ...
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19 views

Determine significance of an observed continuous distribution given many randomly generated continuous distributions

Suppose there is a vector, v, that contains the body height of every person over 30 years old on earth. It looks something like this: ...
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9 views

Selecting samples based on their individual recurrence rates [on hold]

I've generated a population of 100k asteroids >=10m in diameter with several parameters from empirically found distributions of e.g. velocity, diameter, density. From these parameters I calculated ...
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21 views

Multiple Regression - Beginners [on hold]

I'm a beginner in SPSS and statistics, and I'm trying to understand the following. There is an example, which says something about increasing the unit of an independent variable to lead to an ...
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11 views

main advantages of cluster analysis and when is it used?

I've gone through the theoretical definition of cluster analysis and have learnt the basics of it.But i want to know the advantages of the cluster analysis process and a real time example as to where ...
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1answer
29 views

How many replications to eliminate Noise

Marbles marked 1-100 in a bag. You continuously draw 1 marble and then put it back. You only care about marbles 1-10 and want to keep track of how many times you pick those. I'm interested in seeing ...
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1answer
22 views

Sample from a Normal-Inverse-Chi-Squared distribution

Is there a way to draw samples from the following distribution in Python? Unfortunately I wasn't able to find helpful information in the scipy help.
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1answer
117 views

Computation of the marginal likelihood from MCMC samples

This is a recurring question (see this post, this post and this post), but I have a different spin. Suppose I have a bunch of samples from a generic MCMC sampler. For each sample $\theta$, I know the ...
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8 views

How to deal with heterogeneous data set

Problem I have a dataset that contains three types of objects: simple objects, object groups and meta-groups. Meta-groups contain simple objects and groups. Each simple object correspond to an ...
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1answer
58 views

Random sampling distribution question

I have been reading this article on the random sampling distribution (RSD) and non-normal distributions. Basically, if I understand it correctly, the article proposes that the RSD of the mean of a ...
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5 views

Class by class undersampling for imbalanced classes

In multiclass training for Neural Networks it can be a problem when the number of classes is big and the number of training examples is unbalanced between classes. I know of many cost-sensitve modes ...
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19 views

Sampling size question [closed]

I wanted to know the sampling size of a population where size is low and moreover it doesn't follow a normal curve. Moreover I wanted to roll out quality numbers at monthly level as the weekly level ...
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13 views

Order of input data gives different results

The background I am predicting binary target, class 1 is undersampled in ratio 5% to 95%. I have about 120 dimensions. So first I took all samples of class 1 and then roughly same number of class 0 ...
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10 views

Likelihood-weighted sampling and resampling

Suppose we have a Hidden Markov model with continuous state space $X$ and continuous observation space $E$. I'm currently at the very beginning trying to write a code that performs so called ...
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2answers
120 views

Confusing confidence interval question from old textbook

Lets say an investigator reports a 95 percent confidence interval of 1 to 23 dollars per month in reduced utility bills for a randomly selected group of 50 customers who underwent training in ...
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0answers
48 views

What are examples where only a single sample is needed?

Consider the following setup: Let $\Omega$ be a finite (but humongous) state space and $\pi:\Omega\to[0,1]$ be a probability mass function. It seems to me that when people want to "sample" in this ...
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1answer
59 views

Sampling of a Gaussian posterior

Sorry for my simple doubt, but I'm quite newbie and don't clearly get how to sample the posterior Bayesian distribution. My likelihood and prior are normal and I know how to calculate the posterior. ...
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31 views

Modeling the joint distribution of stream statistics

I have a question regarding computing the joint discrete probability distribution of statistics in a number stream. I posted this problem in the Mathematics section as well but I'm hoping the ...
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9 views

Regression and in- and out-of-sample testing for forecasting applications?

Suppose I have a dependent variable, Y, three predictors: X1, X2, and ...
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8 views

How to determine and use the sampling lag in the collapsed Gibbs sampler?

I am implementing a collapsed Gibbs sampler for LDA model. According to this technical note's word, average a number of samples, and often it is desirable to leave an interval of L iteration ...
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5 views

How to evaluate the quality of Bayesian network sampling?

I have generated a sample from a Bayesian network by applying Forward Sampling. I learn the parameters of the network (the same structure) from this sample so as to evaluate the quality of the sample ...
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1answer
52 views

Proposal distribution - Metropolis Hastings MCMC

In Metropolis-Hastings Markov chain Monte Carlo, the proposal distribution can be anything including the Gaussian (according to the Wikipedia). Q: What's the motivation for using anything other than ...
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0answers
5 views

Sampling with Replacement and Excessively Sampling a Few Observations

If I am trying to construct a matched control sample and I am sampling with replacement, there is the possibility that I may select the same observation many many times. What bias could this induce as ...
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26 views

Adaptive sampling strategy

This question (I am sure) was discussed a lot of times, but I could not find an answer (can not make an appropriate google request). It is pretty important: in experimental sciences people spend big ...
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1answer
18 views

How many random samples of a set of N values are needed for a 95% confidence in what N is?

Given I have a set of values N, where N is unknown to me. I can make requests for one sample at a time, which is selected randomly for me. As I request more samples, I see more and more values which I ...
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15 views

Bias and precision in estimating species richness?

I would like to estimate the total number of unique species within a community (=richness, for instance two species: cat and dog) from a randomly drawn sample. I am wondering what is the sampling ...
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17 views

How to determine if sampling is representative to population

Is there any coefficient or some metric that will tell how well sample reflect the population?
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31 views

unbiased estimate for household size

We have a population of N people. They live in households of varying sizes: 1, 2, 3, 4, etc. We are going to do a random telephone survey and ask them how big their household size is. What are the ...
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13 views

Sampling data frame to have 2 level categorical equal probality

I am trying to accomplish the following: 1) I have a dataset with many variables and among them one called Gender, so with 2 levels "M" and "F". 2) I want to sample without replacement this dataset, ...
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1answer
40 views

How to best represent a geographical area as point

I need to check a relationship(?) between land surface temperature (LST) and total population census tract (shapefile) wise where i am trying to relate social factors (e.g. total population, female ...
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1answer
32 views

Basic question about central limit theorem and sampling distributions

The CLT states that "if you have a population with mean μ and standard deviation σ and take sufficiently large random samples from the population, then the distribution of the sample means will be ...
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25 views

Minimum sample size at the last stage of multistage sampling

We're conducting a two-stage survey. First stage is schools, second stage is students. What is the minimum number of students per school that we need to sample? I remember reading that the minimum ...
2
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1answer
39 views

Dirac Delta function Notation

I am trying to understand the delta function notation used to be express a monte carlo approximation of a probability distribution. The notation used in this (p10) is $\pi(x_{1:n}) = ...
0
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1answer
14 views

Sampling. What is the difference between census and random sampling. How do you known how the researcher selects the sample

What is the difference between census sampling and random sampling. For example, a census sample of junior doctors in a 6 acute wards were recruited to a questionnaire survey.
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2answers
27 views

Generating data from a Beta-Binomial distribution by inverting CDF in R [closed]

I am trying to generate data from a beta-binomial distribution by inverting its cdf in R. The code I have written to calculate the cdf seems to be working fine for most cases, but gives me values ...
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1answer
79 views

Are there analytically derivable posteriors that save from doing MCMC other than conjugate priors? [duplicate]

Posteriors for conjugate priors can be analytically derived and save us from doing MCMC. Conjugate priors simply have a posterior in the same family as the prior distribution. Are there other ...
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16 views

Sampling from Irwin-Hall distribution using triangular distribution

So I need to sample from the Irwin-Hall distribution using rejection sampling with the triangular distribution. I built 2 functions: The first is d_irwin which receives an $x\in supp(g)$ and the n we ...
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35 views

Sampling from Irwin-Hall (Uniform Sum) distribution using rejection sampling

Irwin-Hall Distribution is a probability distribution for a random variable defined as the sum of a number of independent random variables,each having a uniform distribution True or False: The ...
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8 views

Evaluate results of algorithm by random sampling

Say I have an algorithm to do something. The algorithm either gives correct result or incorrect result for some data. Now I have a huge data set. I have to calculate the accuracy of my algorithm. If ...
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1answer
23 views

Probability the maximum of N samples was drawn from a given distribution?

I have $N$ samples and I want to know if their maximum $M$ is "significantly" higher than what you would expect -- a sort of outlier detection. I formalize this as: I'd like to know the probability ...
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14 views

Sample Size correction for Times Series

I have weekly time series data time Jan1-Jan7 Jan8-Jan14 Jan15-Jan22 . . . Dec17-Dec23 Dec24-Dec30 Each week there is sample of the total number of people who ...
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1answer
33 views

Data management of a representative sample

In our original database there are some variables which are quantitative, but actually they are categorical variables. Our question is, should categorization be done in the original database or ...
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16 views

reusing previously generated random samples

Suppose, I wish to generate random samples from normal distribution $\mathcal{N}(\mu, \sigma^2)$. I already have a normrand() function. Technique 1 Each time a ...
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22 views

What is the procedure to choose which strata to use if you have multiple strata available?

I have multiple characteristics of a population available (gender, age, place), and I have the answer for each individual for a particular yes-no question available done previously. For example, here ...
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20 views

Sampling from hypergeometric distribution

Suppose there are 1 million balls in the urn. And 1% of those are red, the rest are black. I sample 1000 balls from the urn, and I want to know what's the cumulative probability of getting at least 10 ...
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23 views

Sampling from a distribution using a variable transformation

I would like to draw samples from a pdf $f$. I can write $f$ as $f(x) = A g(y(x))$, where $A$ is a constant and $g$ is another pdf from which I can easily draw samples. Is there a way to first draw ...
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7 views

Minimum/Optimal Training Set Size for a mix of categorical and numeric features

Can someone help explain to me how I would go about determining the 'minimal' training set size I need depending upon how many predictor variables I have and also how many of them are categorical vs ...
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1answer
29 views

Law of total covariance for products of random variables

I have two sets of random variables. $X_i \sim N( \theta, \sigma^2 )$, where $X_i$ are i.i.d. $Z_j$ which are simply iid binary random variables with success probability $p$. I want to find ...
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1answer
34 views

Neyman Allocation Standard Deviation for Proportions

I am currently working towards the Royal Statistical Society's Higher Diploma and have run across a strange result in one of their sample papers that I can't work out - wonder if anyone can help me. ...