# Questions tagged [population]

A population is the entire set of units from which a sample may be drawn.

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### How to estimate population size from repetition in random sampling? [duplicate]

I'm periodically sampling values from what's likely a large population. Millions, let's say. And I'm assuming initially that it's random sampling. However, it's only workable to collect thousands of ...
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### Sample Variance Quandry [duplicate]

I was working on an explicit example for a student of mine, and I ran into a bump. Assume that the population is $\{1,2,4\}$. I draw samples of size 2 (without replacement) from the population. From ...
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### Estimate number of duplicate items in a population by sampling

I have a data source that allows me to pull big sets of numbers (~1e12) with unknown distribution. let's define Mostly distinct as more than MD percent of the population is distinct numbers. For each ...
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### Are confidence intervals only for a specific population parameter, like the mean? What about the whole population range, e.g. for outlier detection?

As someone with quite a weak understanding of statistics, I'd like to know: Is it possible to calculate confidence intervals for a population range in general from a sample? What I have learned so ...
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### Comparing sample mean from my institution to “population” mean pooled from multiple studies

At my institution, we have 40 patients with a certain medical condition. For a particular variable, lets say "days in hospital" we have a mean (3.2 days). We'd love to compare that to previously ...
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### How to standardize fertility ratio?

I would like to know how to calculate the standardized ratio of an indirect fertility ratio, the Child-Women Ratio (CWR) from samples of a population census. What I have read about, is that the ...
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### How do I fit a distribution to summary statistics of population data?

I have a limited set of income data for CountryX. I have the mean, median and percentages (%) of the population that fall within various income brackets. I am trying to work out what percentage of the ...
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### Confidence interval for population proportion estimate with replacement and known total population

So, I have an experiment that is equivalent to having a bag with $N$ balls of various colors in it, then drawing a ball, marking down its color and returning it to the bag. Repeat this process until I ...
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### Conducting “inference” on Titanic data set (and other non-random/“population-encompassing” data sets alike)

Presume I'm given a data set like Titanic, where the data on all the passengers is available (hence "population-encompassing" in the title). Then, by inertia, I proceed to conduct statistical ...
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### Minimum population size for a comparison of treatments

Is there a rule for minimum population size for horticultural experiments and trials? For example, growing a plant variety in 5 different soil types in 5 different locations. My apologies if my ...
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### How to choose at what sample size standard deviation becomes reliable for my purposes?

I'm calculating standard deviation for a normally distributed variable. I'm receiving data samples online, and I've noticed that right after the start (for a small sample size) standard deviation is ...
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### confidence interval for population parameters

This is my second question based on the understanding from this suppose I want to estimate the mean height of all the students studying in 12th class in my state. I do not have access to the entire ...
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### estimating population parameter mean and variance

I have a couple of questions, but I would go one at a time. So what exactly estimates the population parameter. I do not know the mean height and variance of my population, which is sufficiently ...
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### Estimating population mean $\mu$ based on a sampling distribution

I've learned that under certain codnitions I can assume the mean of the distribution of sample means to be approx. equal to the real mean of the underlying population. Additionaly, the standard ...
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### What tests can I run to determine difference in populations on clinic visitations?

I'm not a statistician by training so I'm looking for some suggested tests to determine differences in population distribution. I have the data presented below. A very long list of individuals with an ...
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### Infering population from a sample?

I took a test in class and found it to be difficult. So I asked in my WhatsApp group if others felt the same. 4/36 people replied yes they felt it difficult. Others did not respond either in yes or no....
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### How to calculate the Margin of Error in this specific scenario?

Assuming I have a population made of hotel bookings for a specific period and I need to send a survey questionnaire to each guest (guest=booking) by email. To simplify things, let us assume the ...
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### For the German Tank problem, why do we assume symmetrical samples?

I have read that for the German Tank problem, one assumption to make is the following: 'By symmetry, one would suppose that the number of unobserved labels above X(n) should be about equal to the ...
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### How to calculate probability of observing stage structured census data given a model of population dynamics

I have a rather general question on how I can estimate a parameter, given census data in a stage structured population. I have a deterministic model for population dynamics i.e. J(t+1)= J(t)*sJ + F(t)...
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### Estimating population variance considering both population sample variance AND sampling method variance

I want to estimate the variance of a normally distributed population. I can take N samples and calculate the sample mean and sample variance, which would normally suffice; however, the sampling method ...
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### Communicating aggregate percentage changes in data without exposing individual contributors

So i have a dataset that tracks widget production from 100 different factories, each individually owned and highly competitive. Each line contains the factory name, the date of production, and the # ...
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### What type of data is needed for offset in a Poisson regression model - R

I am trying to do a Poisson regression using the following data, where infant deaths are shown per year for both North and South England. ...
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I have a set of enrollment percentages for every major ethnic group for a study I conducted about a disease I'm interested in. I have the age-adjusted annual incidence rates for that disease, for each ...
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### Large population size = relatively smaller sample size?

Assuming 95% Confidence Level & 8% Margin of Error, a population frame of 37 yields a sample size of 30 (81% of pop) but a population frame of 370 yields a sample size of 107 (29% of pop) and a ...
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### How to know if there is a difference between two populations or if some feature has influence on a certain response variable Y?

I have a database about claims at auto insurance. I can do the math and get Frequency, Severity, Sinistrality. I need to know if cars with automatic transmission have a higher propensity to accidents ...
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### What exactly is the sample size of an investigation?

My understanding of sample size is that it is a portion of the population that serves to represent the population. However, I'm not sure if the sample size of an investigation to investigate how X ...
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### Using mean length and mean weight to calculate mean BMI?

Is it valid to use mean length ($h$) and mean weight ($w$)) from a given population to calculate mean Body Mass Index ($BMI = \frac{w}{h^2}$) for that population?
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### statistical significance of A B test if some observation are removed due to errors

I have ran an A/B test and using chi-square test of independence, results shows that group A improves on group B by less than 5% (statistically significant) YAY!!! Unfortunately, after few checks I ...
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### Find significance between two group proportions

My question is the following: what statistical test would I use to compare the proportion of participants between two groups. For example, if in 2009, 20% of participants ( population was 55) to a ...
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### How can I test the relevance of variables on a dependent variable when I have data for an entire population?

I am investigating factors that influence how certain areas have intensified over time in a city. There are 25 areas which represent all of these types of area in the city. My study is only ...
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### Does significance in correlations matter when I have data for the population? [duplicate]

I am investigating factors that influence how certain areas have intensified over time in a city. There are twenty five areas which represent all of these types of area in the city. I am using ...
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### How to impute distribution by day based on per-week data

I have data from the CDC on the gestational length of pregnancies to the nearest week between 2007 and 2017. This is based on the "obstetric estimate" of gestation since it's rare that the mother ...
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### Dealing with non-representative samples of a larger population

I'm seeking some advice about a project that I am working on. In this project, my colleagues and I are planning on collecting a sample that is intended to be representative of the national adult ...
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### When should a regression be run across the subsets of a population vs the entire population

At work we are looking to run some models on subsets of a population. For the sake of this post, I'll call the models created on subsets 'conditional' and the model run on the entire population '...
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### Estimating the values of unknown subpopulation areas with only the known total population values in R

I probably should have posted it here first, but I have the full details listed on stackoverflow. https://stackoverflow.com/questions/54414182/is-randomforest-appropriate-to-figure-out-if-i-drop-a-...