# Questions tagged [population]

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

421 questions
Filter by
Sorted by
Tagged with
2k views

### 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 ...
70 views

### 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 ...
74 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 ...
45 views

### 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" ...
9 views

### 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: ...
15 views

### 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 ...
16 views

### Why is minimum sample size not based on proportion?

In different situations there are many tests or general agreements for a minimum sample size, which are usually some fixed number that is not that high, capping at <400. Common numbers include 100, ...
23 views

### Confidence intervals: What does the histogram of sample means have to do with the true population mean?

I believe the interpretation of a 95% confidence interval is the following: in 95% of random samples, the true population mean is within 2 standard errors of the sample mean. The 95% number comes from ...
131 views

### How to calculate the range from mean and SD?

Is is possible to calculate or estimate the range of a population if I know the mean, population size and standard deviation? I am doing a research and the mean age of the population is 29.9 +/- 5.3 ...
50 views

1k views

### Detect if there is actually two populations in a sample

I have been counting stomata on fossil leaf material to apply a known relationship between stomatal index and CO2. I thought that the material was all from one population (one species at a given site)....
18 views

### What does replication mean for a mixed model?

I'm struggling to figure out how to test fixed effects appropriately in a mixed model, because of the concept of pseudoreplication (I have only seen this term in the fields of ecology and psychology). ...
40 views

### Additivity of sample (rather than population) variances

I'm trying to use the fact that variances are additive to derive the variance of an unknown random variable. Say that A and B are both independent normally distributed random variables. A third ...
40 views

### Use standard deviation of sample or population in z test

I am reading the book Statistics by Witte & Witte. Some questions puzzle me. Question 10.9: The normal range for a widely accepted measure of body size, the body mass index (BMI), ranges ...
33 views

### Rubin Causal Inference Book Study Question on Subsample and Subpopulation

Page 259 of the book writes: Suppose we look at the subpopulation of all units with $X_{i}=x ;$ within this subpopulation the difference in the distributions of the observed outcomes, between ...
27 views

### Truncated CEF of normally distributed RV. Is sample analogue a consistent estimator of the 'population' truncated CEF?

If I have a random variable that is normally distributed, and truncated such that I only see $y$ if $y\geq 0$, and I want to do some calculations with the truncated Conditional Expectation Function in ...
42 views

### How to sample when the size of the two populations differ greatly

I have to compare the distributions (means, variance, ratio of specific features, etc.) of two populations. However, the sizes of the two populations differ a lot, one with only 30,000 observations, ...
13 views

### Testing Multivariate Group Homogeneity

I have a multivariate dataset with data from several groups. I'm interested in determining at what point are two groups similar enough such that they can be treated as a single group for sampling ...
60 views

### It is possible to find point estimate of population mean and population variance when confidence interval of population mean is given?

Let's say that somehow $100(1-\alpha)\%$ confidence interval of population mean $\mu$ is known as $(a,b)$ and the number of samples is $n$. Is it possible to infer point estimates of population mean ...
12 views

### Another question regarding population proportion:

Here is the link to another question that I asked recently: The answer to my previous question very clearly proves that $\frac{P_sQ_s}{n-1}$ is the unbiased estimator of Var$\left(\frac{X}{n}\right)=$...
41 views

### An unbiased estimate for population variance

Specifically, my notes claim that when calculating confidence intervals for population proportion $p$, the estimator for the population variance is given by $\frac{P_sQ_s}{n}$, where $P_s=\frac{X}{n}$ ...
15 views

### Is my intuitive explanation of the premise for hypothesis testing correct?

They way I understand hypothesis testing is that there is some true data generating process out there, and that determines the 'population' distribution of variables, and then our sample is just one ...
20 views

### Confidence interval over estimated number of infected individuals in a population

I have built a machine learning binary classifier (using a Logistic Regression model) that outputs whether or not a person is infected with Covid-19, based on the symptoms that this person presents (...
47 views

### Statistical Test for Evolution of a Population Proportion?

The problem I am faced with is as follows - there is some population proportion $p$ of people with a certain characteristic that is evolving over time. We take new samples every day (without ...
32 views

### Do we consider the dataset to be sample even if the data we are given is complete data in analytics?

I was watching an online video on statistics and in the video we were making inferences on a real estate companies data, to predict our future customers. The instructor had all the previous data of ...
8 views

### Significance of single classification change across multiple time slices (archaeology)

I'm trying to determine if I'm correctly testing for significance of the change in artifact type presence across several time periods. In an archaeological survey, stone tool artifacts were cataloged ...
50 views

### Is a population parameter really a fixed quantity?

This might be a simple issue. I consistently come across internet sources that say that a population parameter is "fixed" and cannot change. However, if we define, for example, our parameter to be ...
24 views

### Testing similarity of proportions across groups of samples- is ANOVA the right method?

Generally, I'm looking for the correct way to test if samples of a certain population over time tend to have the same proportional distribution more or less e.g. if the amount of certain race in a ...
34 views

could somebody please help me with this question. "What will happen to Confidence Interval if you change from using sample SD to population SD? Would the CI you calculated previously increase, ...
41 views

### Population vs Sample Space

In probability theory, it is my understanding that the sample space $\Omega$ is the set of all possible outcomes of an experiment. In my mind, I am thinking of it as a set of data points such as ...
I am trying to estimate the size of a discrete population $\Omega$. To do so, I draw independent samples $s_1\ldots s_n\in\Omega$ according to some distribution $p(s):\Omega\to(0,1)$. For each ...