Questions tagged [population]

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

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What is the interpretation of outlier-robust principal component analysis?

There's a set of methods called "robust" principal component analysis (here, "robust" means resistant to influence from outliers). One example is Hubert et al., "ROBPCA: A new ...
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What is the meaning of confidence intervals when NOT using sample data and instead have data on the whole population? [duplicate]

I'm trying to understand why you would need confidence intervals or compute statistical tests (for comparing proportions) when your data is NOT from a sample and you have data on the whole population. ...
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Contrasting answers on problem on populations and samples

I recently received this question in my homework assignment: A sociologist wants to study the attitudes of American male college students toward marriage and husband-wife relations. She gives a ...
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If I use entire data, the IPW is effective?

When it comes to causal inference, if I use the entire population data, is Inverse Probability Weighting (IPW) still effective? I have access to the entire population data and need to conduct some ...
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Modeling a population over time given certain parameters

I am trying to model a population over a span of time. The span of time is between the birth of the first person and the death of the last one, say the years 1867 and 2151. Total people born is a ...
92 views

How on earth is a random sample representative of the entire population?

Suppose there are 10k people in the population. You want to find out how many of them brush their teeth. You take 1k of them entirely randomly. They all say "yes". But the rest 9k say "...
184 views

What is the rationale for computing a confidence interval in a study that won't or can't be repeated?

As far as I understand it, when we compute a confidence interval (say a $95$% CI), we have confidence in the procedure, not in the current data we have (as a $95$% CI means that $95$% of confidence ...
1 vote
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Using unsupervised methods prior to cross-validation when all unlabelled data is available

There is lots of discussion about pre-processing methods and if they need to be included within a cross-validation procedure or if they can happen prior to splitting the data -- questions on ...
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The point estimate and the large sample size [closed]

My colleagues and I argued about the point estimate's accuracy. They said that "The point estimate will tend to be accurate if the sample size exceeds 30." While I am saying no, "The ...
14 views

How can I calculate the population size of a collectible from the number of them sold? Best way to quantify rarity?

I'm writing a book on the rarity of antique bottles from a certain state. I want to be able to rigorously define the rarity of a given variant through an estimation of population sizes for that given ...
52 views

How can Bootstrapping explain the uncertainty of a statistic?

I have been reading about bootstrapping, and sampling distributions, and find it odd that people use these techniques to describe uncertainty. As I understand it, the sampling distribution shows ...
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Conceptually understanding specificity

If highly specific tests are usually used for confirmatory testing (and highly sensitive tests for screening), it seems that True Positive would be the most important factor for highly specific tests. ...
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testing difference in distributions with population values (using python)

I am looking for the best method to test for a difference between two distributions. I have data from a patient group, and my aim is to compare the distribution to a reference distribution. However, ...
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How to estimate population size, recapture rate and survival probability with spatial CJS model

I would like to ask for some help. I am new to data analyses in R and I need some help with my current analyses. I need to make a spatial CJS model with normal dispersal to estimate population size, ...
202 views

How to compare fitted survival model with covariates vs. Kaplan-Meier?

How would one ideally compare fitted survival models with covariates vs. a Kaplan-Meier with a goal of getting an idea of whether the survival model describes the data well. E.g. in an example like ...
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Does it make sense to use a hypothesis test with population data rather than a sample? [duplicate]

I have recently been learning statistics from the ground up (for context I am an engineer by training with no formal education in statistics/probability). I have seen various hypothesis tests: z-test, ...
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1 vote
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What relevance do p-values have in a multiple regression of all 50-states (a.k.a. population/census data)

I am running a regression analysis of the U.S. (specifically, the population represented in the U.S. Congress by voting members, so census data for the 50 states would constitute population data). One ...
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Do I need a hypothesis test to compare two populations of complete annual count data?

I would like to compare the total number of public M&A transactions observed in two separate years (e.g. 2021 vs 2022). Given the data set for each year is complete (i.e. a population), can I ...
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Age-sex standardization over study period

I have 10 years of health (number of cases of health outcome, such as asthma cases) and population data, but am using the data cross sectionally because the exposure data are also cross-sectional (due ...
340 views

If anyone could help me verify if my analogy is correct, thanks so much! Here is an analogy: A population is like a pot of soup. We stir the pot of soup with the ladle because naturally the contents ...
36 views

Is it possible to "unpool" a pooled variance if the population variances are not equal?

I recognize that if the population variances are not equal, it's not really a pooled variance to start with, but I wanted to keep the question succinct. The scenario here is that I begin with a sample ...
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1 vote
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Calculating Odds ratio with exclusion criteria

I had a question about how to perform an odds ratio when the group has an exclusion criterion. Let's say I am trying to find the association between surgery and suicide. I wanted to control for people ...
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How to compare U.S. Census demographic data to a population-level dataset? E.g. how to approach a question like are women underrepresented on boards?

I have a population-level dataset of all people who testified on environmental legislation in a single year. I have data on all witness's ages, races, genders, and ethnicities. This dataset is not a ...
40 views

Extreme ends of normal distribution with uneven percentage of two groups

If there are two groups of people A and B which are both normally distributed around the same mean, and 80% of the total group is of type A and 20% is of type B, I know that if I randomly sample from ...
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How does population size impact the precision of the results?

Suppose we want to conduct a poll among a sample from the population. I know that increasing a sample size generally improves the precision of the results, but I was wondering whether given fixed ...
1 vote
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Mixed effects model with data for whole population

I have a dataset about the whole population of interest, not just a sample of it. I ran a mixed effect model where age and sex are fixed effects; urban area where individuals live and country of ...
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How do I present averages from different sample sizes across years?

I have 20 years' worth of observations that either say YES or NO to the question of whether breeding was observed. I want to present the averages of the YES observations across the years, ...
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1 vote
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Statistical significance in known population

I am working with a data set with the sequence identity (a value in [0,1] representing the conservation between sequences) of many genes for many bacterial strains. I would like to be able to draw ...
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1 vote
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Should I use null hypothesis significance testing when I have the full population? [duplicate]

I have data on every species in a genus, and am interested in how two factors relate to each other specifically within that genus. Should I use a statistical test to do this or does it not make sense? ...
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Tools for reporting sample size that contains the percentage of the population

If we have a recorded percentage (statistic) on a population, if we take random samples we might not encounter the percentage till e.g. even we exhaust the population. E.g. a box with $500000$ balls ...
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What should be the significance test when population size is unknown(know that it's more than 1M) and sample size is greater than 30?

I have a dataset with around 1M data. But, in real-life it should be more. From the dataset after first step processing for specific task, I got 50K data. Then I processed it again for a specific ...
602 views

Is Kendall's tau uniquely determined by Pearson rho?

I know that two data sets can have the same Kendall's $\tau$ but different Pearson's $\rho$. What about the opposite? Can two different data sets have the same Pearson's $\rho$, but different Kendall'...
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1 vote
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Age Adjusted Prevalence at region level with only country-level population distribution

I'm trying to calculate age-adjusted prevalence for a bunch of different chronic diseases from hospital data in a specific area and I'm having some difficulty. I have total country level population, ...
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1 vote
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How to determine sample size for non-normal distributed data with continuous variables?

TLDR: I need to determine the minimum sample size for measuring the energy consumption of code. Hello, I'm trying to determine how many samples (N) I need in an experiment to be confident that my ...
1k views

How to combine standard deviations from independent samples?

I have a population of 7954 subjects and multiple random samples from it: 1st sample size 2,665 with a standard deviation 1.386 and mean -7.45 2nd sample size 2,399 with std dev 1.53 and mean -7.33 ...
118 views

Distribution of the point estimator of a sample

We know that point estimator is defined over a sample and is said to be unbiased if its expectation value is same as that of some parametric function $g(\theta)$ where $\theta$ is a parameter for the ...
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1 vote
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Comparing total spent in unequal groups (lognormal distributed)

I have 100K customers from a population with a KPI name "spent" which is lognormal distributed. The customers were split into 2 groups - 1st group - customers with an id ending with 0 - ...
20 views

Population bias in survey leading to inaction

This isn’t exactly an academic statistics question, but it is a real problem that I’m trying to understand with regards to bias in survey statistics leading to issues in real-world decision making. I’...
571 views

Can inferential statistics be used to study an entire population?

I have collected data from all the exercise science degree programs in my nation through databases (thus representing the population under study). I would like to investigate whether certain credits ...
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If all sub-populations are normal, will this population normal?

If all sub-populations are normal, will this population normal? What is this theorem called?
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Understanding the unit used to measure the estimate of population density of bears

I do not have a strong stats background, so I apologize in advance if this is a silly question. I'm currently reading about population density for wildlife. I've read a paper that reports the ...
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Statistics for two populations interacting with each other

Lets say we have a Red team with 1000 members and a Blue team with 100 members. After a year Red team has killed 50 Blue members and the Blue team has killed 50 Red members. Despite both teams killing ...
78 views

Population variance of multiple weighted samples with different sample sizes

I am trying to work out the mean and variance of the fan speed of a turbine across its operational life. The data I have is the timeseries output of N simulations, each simulating a different load/...
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1 vote
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Relationship among exponential distribution, sample size is n, allowed deviation from population mean is X%, then probability of this is %P

I performed monte carlo simulation for various sample sizes with exponential distribution. I set "allowed deviation from population mean" as $5\%$. I iterated $1E5$ times for each sample ...
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1 vote
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Noob question: What population data do I I need to give the probability that the X is higher than the Y when both are randomly selected?

In explaining population differences to non-statistically minded people, I often find it helpful to frame a fact like this: If you pick a random woman and a random man from the population, there's a ...
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Can Positive Values of Observations imply Population Positive Mean?

Suppose that we have N-observations for a random variable $V$ from a population: $$\{v_1,\;\ldots,\;v_N\}$$ , and all of the observations is positive: $v_i>0\quad \forall i=1,\;\ldots,\;N$. Here, ...
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Why do two different population sizes result in nearly equal sample sizes?

I have calculated the sample size for two different populations, N1= 29414 and N2= 625 (see code below). Why do I almost get the same sample size n1= 380 and n2= 239. There is not much difference, ...
1 vote
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How to infer unknown cell frequencies (effect of a variable) if table marginals are known and cell frequencies for another population is known?

I want to infer cell frequencies (or conditional probabilities) for a population table where: I know the marginal totals but not the cell frequencies, and I know the cell frequencies for a table of a ...
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Does the population mean differ significantly in calculation from the sample mean after multiplying by 1/n?

The expectation of a binomial distribution is given by E(X) = np, where n is the number of trials and p is the probability of each trial. When using a normal distribution to approximate the binomial ...
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1 vote