Questions tagged [population]
A population is the entire set of units from which a sample may be drawn.
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Compare means between samples, while controlling for sampling differences - valid to use regression this way?
There are two independent samples of people, drawn from a population of a city at times $t_1$ and $t_2$, a decade apart*. The people were asked rate their preference regarding some question $Q$ on a ...
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7 views
Conditional Probability Based on Sample When Population is Known
I have a count from each U.S. state of people that ride bikes. I want to know whether the count is larger or smaller than expected relevant to the population of each state (I also have the population ...
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Determine Sample Size [on hold]
In determining sample size, how to analyze this problem.
You plan to sample students from each of the following strata: Sophomores, N=1000; junior=N=500; Seniors, N=300. Answer the question below.
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1answer
39 views
Deciding on population vs. sample
I have been researching when to classify a dataset as population vs. sample for many hours now for a statistics project I am doing. I have a dataset of NFL combine data and one thing I need to clarify ...
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Intuition for why the “interaction variance” in an ANOVA is an estimate for the population variance
As I understand it, the general idea of the F-test is to exploit two different ways of estimating the variance in the population if all values actually come from a single population (see my reply here:...
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1answer
34 views
Estimation of a population number
Suppose that we know the population number $n$ of a country in $2014$ for people aged between $0$ and $19$ years what would be a good simple way to estimate the population number between $1$ and $18$ ...
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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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1answer
26 views
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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1answer
42 views
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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23 views
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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17 views
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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23 views
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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15 views
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-...
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1answer
28 views
Test hypothesis against true population distribution
I have drawn a sample from a population. For an hour I have asked all the visitors to a website their age.
population = people in Germany
sample = 32 German visitors to the website
(international ...
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1answer
16 views
Is it possible to estimate a population mean from a convenience sample?
I have data for which I can compute a sample mean. These samples are certainly not random. Is there any way to make an estimate of the population mean from a single biased sample?
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compare distribution a categorical variable between a population and a subpopulation
So I have the following situation of having a population P with individuals belonging to categorical variable A, ..., N. From this known population I created several sub-population P1, P2 (each time ...
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Sampling theory of correlation; sign of population correlation coefficient & hypothesis design
I'm currently studying 'Estimation of population correlation coefficient from sample correlation coefficient.
Source: https://newonlinecourses.science.psu.edu/stat501/node/259/
Test statistic is like ...
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2answers
117 views
Calculating the variance of sample, knowing the mean of population
Suppose that I somehow know the mean of the population. And I want to calculate the variance of a sample.
Should I subtract population mean or sample mean?
Is there any situation in which I should use ...
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14 views
Range of population variance [duplicate]
I have a set of numbers between 0 and 1, for instance, {0.4, 0.1, 0.0, 0.8}. What are the minimum and maximum values of population variance on such set?
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1answer
36 views
Population Mean Estimation using Poisson Regression?
Assuming I have count data, where x is the counted variable of interest and y is some total number of counts for a given sample. Then, can I improve my estimate of $\mu_x$ by using a Poisson ...
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67 views
Is my Correlation reasoning correct?
I am trying to understand how to arrive at $r = \dfrac{Cov(X,Y)}{\sigma_X\sigma_Y}$ with a logical narrative. This in fact is kind of continuation from my this unanswered question.
I see that by ...
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45 views
Time series: sample vs. population, population vs. realizations of random process
Suppose we have 120 monthly observations (Jan 2000 - Dec 2009) of unemployment rate and suppose we would like to use these in order understand the unknown underlying stochastic process that generated ...
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2answers
135 views
How do I compare means when I have a sample and the whole population?
I have the following didactical exercise to carry out:
Scenario
I have the avg room price for all the hotels of my chain (32 observations of the 32 hotels). Then I have the avg room price for a ...
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2answers
41 views
Testing that training and test data sets (not vectors) have been drawn from the same population in R
I have two data frames in R (training + test). The test set is not drawm splitted from one sample by myself but I got those two dataset and am supposed to built the model on the training set and make ...
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1answer
53 views
Two-sample T-test
Hi I conducted the research where I measured germination of seeds in different ecological conditions. Each seed sample (one germination data) was exposed to different combination of ecological ...
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30 views
Likelihood that two random sample sets come from the same population
I have two random sample sets of 100 points, with 7 possible answers (A – G) each. The sets are as follows:
Set 1
A 49
B 22
C 14
D 7
E 4
F 4
G 0
Set 2
...
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22 views
How to calculate whether a disease outcome in a population is by chance or significant?
I have a huge dataset of longitudinal medical records. Each record contains indications for drug and disease.
I have been able to calculate the Outcome Rate in the population given a particular drug....
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2answers
145 views
About Sampling and Random Variables
So I've recently started an introductory course in econometrics and I'm having trouble grasping the idea of Random Variables and Sample distributions
If we have a population and we take a sample $Y= \...
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22 views
Comparing averages of unequal population sizes
Imagine the following problem: I have 1000 plots of land. On each plot of land I plant 1000 Oak trees and 1 Elm tree. Each plot of land differs in multiple parameters (e.g. sunlight, soil type, ...
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93 views
Comparing sample correlation coefficient with population correlation coefficient
Assume there is a population, P, of size N. Each member of the population has three variables associated with it, a nominal variable C (with m unique categories), and two continuous variables X and Y....
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1answer
34 views
How to find a population of healthy products among many samples
A measurement is performed on 100 equal products. Some of these products contain defects. I expect defects to be present on a small number of products, say a total of 10. Now I want to create a ...
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20 views
Update to estimate of population mean based upon new sample
Suppose I sample some phenomenon with a potentially moving mean, let's say height of males on their 18th birthday, and I run this survey every year. Each year I produce a sample mean of height, which ...
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Confidence intervals interpretation in whole population studies. Can they represent replication variability?
I got the surgery time of each surgery ward patient. I want to compare the mean surgery time of each ward using a series of regressions in which the independent variable is being or not in a specific ...
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1answer
48 views
Is this conclusion drawn from sample or population?
"When asked what they would use if they were marooned on an island with only one choice for a pain reliever, more doctors chose A than B, C or D."
Is this conclusion drawn from population or a sample?...
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12 views
Population Stability Index: Why ln not log? [duplicate]
The Population stability index is based on natural logarithm.
http://ucanalytics.com/blogs/population-stability-index-psi-banking-case-study/
The formula looks somewhat similar to what I have seen ...
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0answers
41 views
Interpreting PCA, comparing genetic structure within mice population from two continents
I'm interested in comparing the intra-regional genetic relatedness between two populations of mice. One population is native to Europe, while the other is native to North America.
I ran PCA to find ...
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1answer
39 views
Counting Number of People in Building Given Entry/Exit Data
I've been asked to analyse entry/exit data for an office to find out the minimum number of people present in the building for fire safety reasons. The building operates 24/7 so there should always be ...
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1answer
37 views
Simulating samples from a population based on marginals
In Germany's health care system, health care expenses $Y_i$ of individual $i$ in a given year are explained by $K$ dichotomous risk factors $(X_{1i},\dots, X_{Ki})' \in \{0,1\}^K$. The multiple linear ...
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1answer
32 views
How to find mean and variance of population of flat probabilistic distribution
I'm trying to understand the difference sample variance and population variance and how former converges to latter after ...
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20 views
Quantifying similarity of two objects in a population on certain characteristics
I have a set of objects (these are businesses) and for these businesses I have data on a number of characteristics. To keep this simple, we will consider these to be
number of staff
number of ...
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19 views
Comparing population averages while accounting for changes in composition
I have two populations (i.e., men / women) with different average measurements (let's say height). I observe the combined average of their height decreases. I also observe the proportion of women ...
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0answers
22 views
Statistical Control vs. Sample Representativeness
Assume I have a sample that is NOT representative of the population.
To illustrate an example, assume I the dependent variable called Violations that measures the number of job violations, and I ...
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0answers
16 views
Age-adjusted rate across many years
I have incidence-level data for heart disease that includes patient age and region. I calculated disease counts by region and now I want to calculate an age-adjusted rate for each region.
The data ...
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0answers
10 views
Multi-tiered (nested?) uncertainty & confidence bands - subset populations
I have a current and historical dataset of likelihood that a population gets into a car accident. I have my predictions for a rare event - say the % chance that a given driver gets in a car accident ...
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37 views
Can populations of different sizes be compared sensibly?
I am new here but have a question about population comparisons.
I am trying counting pollen grains using an Scanning Electronic Microscope (SEM). I want to compare the abundance of a certain type ...
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1answer
33 views
Why does a sample of n of a population of n retain degrees of freedom of n?
I understand that if you take a sample from the population that a single data point cannot freely vary if $\bar{x}$ is known and you have the remaining sample items. However, I do not understand why "...
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26 views
How to analyze size frequency data from over 70 sites
When I started my PhD, I had virtually no prep-time. My advisor needed me in the field and told me to go grab samples. As such, my planning wasn't the best, so sorry if this is a completely terrible ...
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1answer
191 views
Getting the probability of a sample being between two values
I am learning on probabilities in populations and samples now but I'm stuck on this question.
Suppose we have a sample with n=35 of a population with a mean of 80
and standard deviation of 5.
...
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37 views
Identify the underlying distribution from multiple samples
I have $30$ unequal samples ($n_i >1000$) from a supposedly same population. How should I go about identifying the underlying distribution of the population using these $30$ samples simultaneously?
...
