Questions tagged [population]
A population is the entire set of units from which a sample may be drawn.
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How to interpret 'e' in Yamane's Formula?
If I use e=0.05, and from Yamane's formula I obtain, say, a sample size of 300 from given population size. Now, for instance, I obtain some descriptive statistics from the sample size such as the mean ...
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two proportion z test with large population
I want to test for differences between two proportions, specifically, a complete count of the number of events occurring within a population in year 1 vs that in year 2. I thought a two proportion z ...
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1answer
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Why do 95% confidence intervals contain the unknown population mean 95% of the time?
I am learning about the Central Limit Theorem (CLT) and confidence intervals from this online course.
I have learnt that that the CLT states that the theoretical sampling distribution of a sample ...
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When we up-sample the training set, don't we introduce selection bias?
When doing supervised machine learning in the health or medical domains, we often have a target class that is relatively rare (e.g., prevalence 1-10% of cases). There are a few techniques we can do to ...
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How to study data variance with significant and non-significant regression response?
Background
My research field is within development of Finite Element Human Body Models (FE-HBMs) with the aim of including geometrical population variance (3D shape). My background is not in ...
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Practical use for heritability value at sub-population level?
For me as a layperson, heritability is something that much smarter people than me calculate, and there are several questions already on the forum about how to do that (eg, this and this). I ...
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20 views
Stratified Sampling from a population according to given weights
I have a population and i want to take a sample from it in order to examine a mean of a characteristic (say $p$ the probability of having an infringment).My population is 13996 and are divided into 7 ...
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How can you compare changes in a shifting population over time?
How can you compare changes in shifting population over time?
For instance, say I have the proportion of retired people in a town at time 1 (T1), then again at time 2 (T2). The "population" ...
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Central Limit Theorem: Is the likelihood of obtaining some sample mean exact when n is not infinity?
The central limit theorem states:
$$ \lim _{n\to \infty}{\sqrt{n}}{\left({\frac {{\bar {X}}_{n}-\mu }{\sigma }}\right)} \sim \mathcal{N}(0,1) $$
Which means if I ran an infinite number of experiments, ...
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What do "random sample" and "particular population" mean in clustering?
Yesterday, from a suggestion of @Dimitriy V. Masterov here, I saw from the given link about one of the reason we can avoid clustering is
You want to say something about the association between ...
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1answer
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Why a variance of a sample mean is the population variance divided by a sample size?
On the wikipedia page about variance I have found the following equality
$$ Var(\overline{X})=Var(\frac{1}{n}\sum_{i=1}^{n}X_{i})=\frac{1}{n^{2}}\sum_{i=1}^{n}Var(X_{i})=\frac{1}{n^{2}}n\sigma^{2}=\...
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Population growth projection
Que ) Population grows in such a manner that [1/P(t) ] dP(t)/dt is a linear function of log P(t) where P(t) is the population size at time t . Obtain the explicit expression for P(t)*
In this question ...
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1answer
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How do you know from what population a sample comes?
My question is say you take a sample say of people weight and you get in pounds right [100,220,230,240] many people say this sample come from a normal distribution population.
But my question is from ...
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What's the population inclusion criterion in an unpaired two-sample t-test?
I'm conducting a clinical trial in London, UK on 200 women suffering from breast cancer and would like to investigate the difference in a biomarker's concentration (continuous variable) among two ...
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1answer
16 views
Statistical considerations when working with population data
My statistical training has been under the assumption that I will never have access to population level data. In my current role though I do have access to this level of data for a region.
Are there ...
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Comparing segregation of populations
I am trying to work through some data and statistical analysis a predecessor has already done. I have two populations of n individuals that were evaluated multiple times in multiple years. So every ...
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1answer
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Difference inference about x datapoints in sets vs subsets
I have been wondering about a theoretical question regarding statistics. So if I understand it correctly, in the frequentist tradition we want to make inferences from a sample to a population (of ...
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1answer
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Normality for population and sample [closed]
I'm new to statistics and got to the point normal distribution. can we define normality for samples too or they're just for population?
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binary variable sample values to population distribution
What seems like a very basic stats question, but yet I wouldn't know the answer and its quite hard to find. Here we go:
Say I have a population of 30 organizations. I want to know whether within this ...
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19 views
Comparing a population mean with another population's sample mean
We are currently studying a difference in ESG performance between two groups of companies and initially looked at doing a two sample t-test but now have a question on which method to use since we ...
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31 views
Can statistics from a certain country be used in another country?
This is my first time posting a question on a forum-like site, I hope my question is not out-of-topic and I'm writing clearly enough.
So, I came across some tweets about the distribution of wealth ...
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1answer
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Why do we use term “population” instead of “Data-generating process”?
I have always been confused about the use of the term “population” in statistics. In my first statistics course I was taught that we need a sample, because surveying the whole population is too costly....
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Hypothesis Testing and Z-test for happiness at work
I'm doing a school project and decided to look closer into this COVID-19 thing that is obviously going on at the moment. I have a hypothesis that people in teams (at work) are happier at work after ...
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1answer
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How can the US have a positive population growth (0.5%) with a < 2 fertility rate? [closed]
Google states that the US has a fertility rate of ~1.73 and a population growth rate of ~0.5%.
It seems like anything less than 2 for a fertility rate should result in population lessening. Is my ...
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K-means to Uncover Finite GMM Parameters in Population Case
Given a finite Gaussian mixture model with the number of distributions known, will k-means reveal the true mean parameters of each Gaussian in the infinite population case? I assume generally not, but ...
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Chi-square test where sample is the population
I have Likert-scale survey data in which the sample is 97% of the population (181 out of a possible 188 respondents). I have tried to follow the complex debate about the need and value of statistical ...
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1answer
38 views
Sample and population: definition for workplace statistics?
This might be a bit of a dunce's question, but I was wondering about the difference between a sample and a population.
Obviously, if you have data relating to 200,000 people but you only look at 200 ...
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EDA and Data cleaning can be done before selecting data samples from population?
I have a huge dataset from which I need to select a sample for machine learning. The data set has high NAN and noise. Hence is it good approach to do EDA, cleaning before taking samples?
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How to calculate proportion of the population
I am trying to calculate population attributable fraction. The formula that i am using is
$$
\frac{P_e(RR-1)}{P_e(RR-1) + 1}
$$
I am using this website as guide: https://sphweb.bumc.bu.edu/otlt/mph-...
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31 views
Sample or Population Standard Deviation (SD) While Calculating SD Regarding All Variables' Variance Inflation Factor Values
What Was I Trying to Do?
I was calculating the Variance Inflation Factors (VIFs) of all variables in a data set. Then, I was interested to calculate the mean and standard deviation (SD) of VIFs of all ...
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1answer
38 views
How to account for population sizes when comparing percentages (not CI)?
Let me articulate my line of thought.
Imagine that you're working for the ministry of transportation. We compare two countries. One country is significantly bigger than the other – for example we ...
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1answer
13 views
How do I find population mean μ for a value that has uncertainty
I have a value x = 60 ± 5.5, and I want to find the population mean μ_x (mean of x), and the population variance of x. How can I do do this?
Sorry for the noob question, but I've spent 3 hours trying ...
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2answers
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Does it make sense to use a population parameter like $\sigma$ (population standard deviation) in the formula for SE?
Correct me if I am wrong but in the formula for SE
$\text{SE} = \sigma/\sqrt{n}$, the numerator refers to population parameter.
But in practical life, we resort to sampling because we don't know much ...
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Comparing populations of greatly different size
I'm reading an analysis someone gave me comparing two different populations of loans. One has about 3,000,000 loans and the other has about 6,000. The analysis compares the percentage of defaults in ...
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How to determine "per" population size for incidence rate
I am reading notes for a given assignment and incidence rate is defined as
$$
\frac{new cases}{observed population} x 10^n
$$
The only thing that is confusing me is that what to use for ...
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How to test if the subset is representative to whole dataset
I would like to ask how to test if the subset is representative to the whole dataset.
I have for example 150 values in whole "population" and I selected (not randomly) 30 of them. I would ...
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how to test auto-selected sample and modify it to represent population
Suppose you have responses from a survey on an entire population, i.e. an organization of 5000 people. All has been invited to respond. Only 65% of them did. Assume also you have the ground truth of ...
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How to compare sample and population characteristics?
I have a sample $S1$ of 200 people, and I obtained a subsample $S2$ of 100 people by emailing a survey link to $S1$. So, $S2$ is a nonrandom subsample drawn without replacement.
In the sample $S1$, I ...
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1answer
58 views
Terminology - population and sample in repeated rolling dice experiments
The the law of large numbers wikipedia page has an example on fair, six-sided dice:
According to the law of large numbers, if a large number of fair six-sided dice are rolled, the average of their ...
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Determine item level variance of single test administrations as well as of an entire sample of administrations
I am decades out of school and need help determining the correct statistic / concept to use for my use case.
My agency (human services) uses a specific functional test to determine how well clients ...
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1answer
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How statistically relevant are COVID information about the number of infections per day?
I am French and the restrictions in place in my country are driven by several indicators, including "the total number of infections per day". For reference, it is currently given as about ...
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Is “$\mu_{\bar{x}} = \mu$” the same thing as saying the mean of the population is the same as the mean of the sample?
My e-textbook is telling me that, when finding a sample from a population using a normal probability distribution $\mu_{\bar{x}}$ is roughly equal to $\mu$. It then gives me a problem asking me to ...
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How to forecast temporal series and have them match with external values?
I have a hierarchical population dataset with 3 grouping variables (Age, Gender and Urban/Rural Setting).
I would like to generate predictions at the bottom-level (i.e. disaggregated at Age * Gender * ...
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1answer
61 views
Is there a difference between a population and a set of realisations of a random variable?
Is there a difference between a population and a set of realisations of a random variable? I heard that a sample of a random variable is a set of iid duplicates of the random variable as a process, or ...
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4answers
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How do we decide when a small sample is statistically significant or not?
Sorry if the title isn't clear, I'm not a statistician, and am not sure how to phrase this.
I was looking at the global coronavirus statistics on worldometers, and sorted the table by cases per ...
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2answers
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statistical method for finding significant numbers in a set [closed]
Suppose that we have a population of $N= 1000$ people and they want to select 5 items (for simplicity) $\{A, B, C, D, E\}$ (but actually number of items is in the order of thousands). Number of ...
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548 views
Is heights of humans actually a discrete random variable? [duplicate]
Suppose the human population consisted of $N = 3$ people, each with a specific height. Let $X^N$ be the random variable representing the heights of this population of $N$ people. Since $X^N$ can only ...
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1answer
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Population vs. Data-Generating Process
A lot of elementary statistical and econometric literature bases on so called "population models". An example is econometric handbook "Introductory Econometrics: A Modern Approach" ...
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Re-calibrate interaction matrix in population sample
Let's say I have a population {$(G, p)$} where $G$ is a group within the population, and $p$ is their proportion distributed as such:
...
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1answer
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Sub-population analysis
I'm facing a statistical issue.
I'm analysing a medical dataset, in which I have a full population. I know if they have a certain disease or not.
Let's say I have 100 000 people on this, 20% having ...
