Statistical Analysis Stack Exchange
Statistical Analysis Stack Exchange

Questions tagged [sample]

a sequence of objects or individuals collected from a larger (possibly infinite) population or process.

In practice it is rarely possible to take measurements from every object composing the population of interest. Hence, statistics, in general, is concerned with using samples to make inferences about the parameters governing the population.

There exist different strategies for selecting representative samples from the population, such as random sampling, stratified sampling, and longitudinal sampling, among others.

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Generalizing results - what is the population?

Take as an example the well-known Boston housing dataset. In the original paper, the regression model was used to model the amount people were willing to pay for improved air quality. But the 'people' whose behaviour was being modelled was never…
DavidP
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What is the minimum sample size for discrete choice experiment?

I was wondering if there is a minimum sample size for conducting discrete choice experiment. From what I know, if choosing the number of sample size is a problem, one can resort to using the magic number of 400+. Although it would be nice to have…
archie
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Why cannot a sample of voluntary patients be generalized?

In the book “OpenIntro Statistics” it is specified that samples of voluntary patients cannot be generalized. Why cannot a sample of voluntary patients be generalized?
SunnyShah
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How to write the formula of Sum of Squared Deviation with SD and n in R?

mathematical formula to calculate standard deviation is $SD = (\frac{SSD}{n-1})^{0.5}$ Would like to find SSD and how to write in r ? SSD = ????
Learner
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Calculating sample size with standard deviation?

Okay so I have an exam coming up pretty soon and I really can't get the hang of how to calculate sample size when all you are given is standard deviation. For instance: A normal population has a standard deviation of 15. How large a sample should be…
SSQ
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When can a pilot sample be included in the main study?

For example, when estimating the proportion of database records that agree with paper documentation. Auditing each record is tedious, so it is tempting to include the pilot sample in the main study (once the required main sample size is estimated).…
nacnudus
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Samples from a black box

Say I have a black-box that contains a lot of numbers (integer numbers). The quantity is very very large and the range of the numbers is finite but unknown (the numbers can be repetitive). I want to know what would be the minimum amount of samples I…
Bur Nor
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What is the difference between sampling variation and sampling error?

I was watching this video and resampling from a sample (bootstrapping). He refers to both sampling variation and sampling error. What is the difference between these two terms? Is sampling variation the concept that there is difference between the…
Christopher U
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Sample from a distribution constructed by Dirac measures

I am reading the paper in the following link https://link.springer.com/article/10.1007/s11203-009-9037-8 In the page 19, the author suggests to sample $\eta_i$ from the following distribution $P^{\eta} =…
Fly_back
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Comparing two samples with values form different distributions

I came across the problem of comparing two samples children's. For each child, I have age and BMI value, I also know if he sports or not. I want to decide, if the children who sport have better BMI values that those who dont. The problem is, that…
jdoe
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help with sample size calculation

hi im conducting a study on a certain ratio in a blood exam (lets call it X) . I aim to say that there is a certain sensitivity (let say>80%) for people to be sick if X>10. (my actual intent is to check the sensitivity for different values of…
urilee
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How to report sample size of an experimental study in a thesis based on power analysis?

I am not sure whether I have reported the sample size properly in my thesis which I have calculated based on power analysis. Please a have look: Based on a power analysis, the desired sample size for this study was 128. Given an expected medium…
Arifur Rahman
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Statistical significance of a small sample binary test

I work at a hospital in a coastal area that is prone to flooding. The hospital has a long list of tasks that are performed in the event of an emergency, and a large (over 1,000) set of organizational units that those tasks are doled out to. They…
jerH
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Definition - Simple random sample

In a textbook of mine I detected the follow definition of a random sample: "Every possible sample of size n has the same probability of being selected" However, I also already saw some definitions that are formulated like the following: "Every unit…
Made
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What is target and sample population? the portion of population for whom we have received data or those who were invited to participate

I am new to statistics and I am trying to understand target population and sample data. Suppose a company wants to know the level of satisfaction of all their customers. To this end, it has sent a survey questionnaire to a portion of its customers…
Josh
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