# Questions tagged [sample]

A sample is a subset of a population. Statistics, in general, is concerned with using samples to make inference about the parameters governing a larger (possibly infinite) population.

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127 views

### Compute (bootstrap?) expected difference between two samples

What would be the correct (most statistically sound) way to tackle the following problem: Given are two samples (or empirical distributions) from two unknown distributions $X$ and $Y$, with $N_x$ and ...
237 views

### Samples size with sample proportion close to 0 or 1

For a future monitoring program on small water bodies we want to calculate the sample size. The bodies of water are so small that their number easily exceeds 100.000 in the monitoring area and ...
126 views

### Does this sampling without replacement have a name?

There can be many ways and ad hoc variants to perform sampling without replacement from a limited population. Consider we have $k$ categories (types of objects) and the k-length vector of their ...
155 views

### The practical use of the lower/upper semivariance adaptation of Chebyshev's inequality for sampled data

The wikipedia article about Chebyshev's inequality also lists a one-sided sharpened variant, based on upper/lower semivariances. It is additionally mentioned there there that "The inequality with the ...
754 views

### Measure of similarity between two multivariate samples

I have two samples from a multivariate distribution. One is approximate and the other is exact. My aim is to measure the similarity between the approximate sample and the exact sample. In particular, ...
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### Does sampling fraction matter for McNemar's Test?

For McNemar's Test, does the sample need to be less than 1/20 of the population if the sample is without replacement? If so, can I correct for a sample that is larger than 1/20 of the population by ...
193 views

### Population, sample and model

Background: In Statisical Methods by Pfaffenberger and Patterson, they say that "A parameter is a numerical measure of a population characteristic." (p. 306) "A statistic is a numerical measure ...
141 views

### bound on expectation of a two-variable function under an independent distribution

Consider a probability distribution $P(x)$, a set observed samples $S = \{x_1,\cdots, x_n\}$ where $x_i \stackrel{iid}{\sim} P(x)$ for $i \leq n$, and a symmetric function $h(x,y)$. How can one ...
153 views

### How to evaluate similarity of datasets based on summary data?

I have summary data that I want to compare to my own data. For the summary data I do not have access to the underlying data, however, I know the percentiles as shown below (A). I also calculated ...
62 views

### Estimating the mean from knowing the first n largest values

There is a sample of n values that are the first n largest values of a population. Is there a way of getting any statistic such as mean or dispersion from such piece of information provided that the ...
286 views

### How to calculate the 'loss' in information when decreasing sample size?

I have a questionnaire with ~40 questions where the respondent answers on a scale 1-7 on each question. At the moment we have a sample size of say 10,000 people. The question is how I calculate the ...
47 views

### How to estimate log-normal distribution parameters from a set of data?

I don't have any background in statistics, so maybe I may say things that are incorrect. I have to model the production of waste deposition at each container of a set of containers and I have access ...
16 views

### Expected standard deviation of probabilistic sample

Let's say I have a collection of $n$ individuals, each individual is associated with a single value $x_i$, with $i = 1, 2, 3, ... n$. I now gather a sample of $s$ individuals from this collection, ...
21 views

### Logit regression (Panel data): resample?

I have a panel data (all listed companies in the US with quarterly data) in which the dependent variable is 1 if the company was recommended on a investment recommendations website, and 0 otherwise. ...
35 views

### Unbiased Estimator of the Standard Deviation of the Sample Standard Deviation

I'm looking for an unbiased estimator of the standard deviation $\text{SD}(s)$ of the sample standard deviation $s = \sqrt{\frac{1}{n-1} \sum_{i=1}^{n} (x_i - \overline{x})^2}$. I have found this ...
38 views

### Why is unbiased estimation from a sample only possible for certain properties?

I was thinking about finding some monotonic measure of entropy of a sample from a continuous distribution (2D, btw), but couldn't think of any such without making assumptions. Why is it that one can ...
66 views

### Time series: sample vs. population, population vs. realizations of random process

Suppose we have 120 monthly observations (Jan 2000 - Dec 2009) of unemployment rate and suppose we would like to use these in order understand the unknown underlying stochastic process that generated ...
16 views

### Evaluating usefulness of estimations of a parameter for different distributions

If I had a sample of size n and wished to estimate some parameter, say p for two different distributions from the produced sample what would be required to determine which was more useful? Assume the ...
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### Sample size for comparing two properties of time series data

I have a dataset of observations of two properties of an object (x and y), which are distributed over time, ...
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### Determine how much and why a sample differs from its population

I'd like to be able to determine a) how much and b) why a non-random sample “differs” from the population (there's probably a better word than “differs”; I was tempted to use “does not represent” but ...
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### Is a sample of 1961 people out of a population of 225,000,000 a sample size that is too small? If so, why?

I am working by a set of problems on a single question in my textbook. The question explained that there was a recent survey of 1961 adults out of a population of 225,000,000 and asked me to construct ...