# Questions tagged [sampling]

Creating samples from a well-specified population using a probabilistic method and/or producing random numbers from a specified distribution. As this tag is ambiguous, please consider [survey-sampling] for the former and [monte-carlo] or [simulation] for the latter. For questions regarding creating random samples from known distributions, please consider using the [random-generation] tag.

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### Which one should be applied first: data sampling or dimensionality reduction?

I am working on binary classification problem. Data set is very large and highly imbalanced. Data dimensionality is also very high. Now I want to balance data by under-sampling the majority class, and ...
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### Multistage sampling in R

I've got a dataset similar to this: ...
650 views

### How much undersampling should be done?

My aim is to predict quarterly customer-default probabilities: I have data on ~ 2 million individuals, who default on average with a probability of ~ 0.3 percent. Therefore I am thinking about ...
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### Calculating required sample size, precision of variance estimate?

Background I have a variable with an unknown distribution. I have 500 samples, but I would like demonstrate the precision with which I can calculate variance, e.g. to argue that a sample size of 500 ...
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### Is “every blue t-shirted person” a systematic sample?

I'm teaching an intro stats class and was reviewing the types of sampling, including systematic sampling where you sample every kth individual or object. A student asked if sampling every person ...
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### Sample selection and variation in the variable of interest when using panel data

I wonder how to reason when selecting samples. I am doing a panel data regression analysis about how the euro membership correlates with the budget deficit in the member countriues. Using R that is: ...
996 views

### Balanced sampling for network training?

I have a very unbalanced sample set, e.g. 99% true and 1% false. Is it reasonable to select a balanced subset with a 50/50-distribution for neural network training? The reason for this is, that I ...
741 views

### Optimal stopping from an unknown distribution

The Secretary problem has an algorithm for fixed N and immediate accept/reject (that is, reject reject ... accept one, stop). There are several variants; in mine, secretaries or samples come from a ...
311 views

### Survey Sampling: What am I missing with this plan?

Working off a fairly limited statistical understanding, so apologies in advance if this question is ludicrously basic. This has to have happened to other people who have successfully solved this ...
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### How to re-sample an XTS time series in R?

I have an irregularly spaced XTS time series (with POSIXct values as index type). How can I build a new time series sampled at ...
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### Statistical inference when the sample “is” the population

Imagine you have to do reporting on the numbers of candidates who yearly take a given test. It seems rather difficult to infer the observed % of success, for instance, on a wider population due to the ...
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### Managing error with GPS routes (theoretical framework?)

I'm looking for the appropriate theoretical framework or speciality to help me deal with understanding how to deal with the errors that the GPS system has - especially when dealing with routes. ...
621 views

### Estimate the size of a population being sampled by the number of repeat observations

Say I have a population of 50 million unique things, and I take 10 million samples (with replacement)... The first graph is I've attached shows how many times I sample the same "thing", which is ...