Questions tagged [population]
A population is the entire set of units from which a sample may be drawn.
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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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0answers
11 views
Adjusting proportions for incidence
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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0answers
12 views
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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9 views
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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2answers
33 views
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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3answers
2k views
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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16 views
True covariance matrix in Monte Carlo simulation?
In a linear model, such that Population model is
$y_{it}=\ {\beta_{i1}f}_1+{\beta_{i2}f}_2+\cdots{\beta_{ik}f}_k\ +\ \varepsilon_{it} , i = 1,2,3...,p$ and $t=1,2,3,...T$
and
$\mathrm{\Sigma_y}\ =\ ...
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3answers
335 views
How to figure out whether the data is sample data or population data apart from the client's information?
What are the ways available to figure out whether the data is sample data or population data apart from the client's information?
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1answer
30 views
Why is the infinite-population perspective usually taken in sampling? What underlying bias/convergence implications are there?
In sampling literature and causal inference literature, there usually is a distinction made about how to view observed data. The first is usually to view some observed data as having come from a ...
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10 views
How to calculate Fst from multiple loci?
I am having a lot of trouble calculating correct Fst values for my SNPs. Whilst my data doesn't have any population in it, I have added pop as a factor, separating my data into 4 different populations....
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1answer
32 views
How exactly can I get sampling distribution of means for calculation of standard error?
Let's denote population by $ N $ and sample with which I want to make inference about $ N $ denote by $ n $.
Let's assume I have already collected $ n $. Now I want to get means for sampling ...
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1answer
43 views
Sample is almost the same as the population
I'm interested in a situation where I have a small list of events, somewhere in the range ten to a few hundred.
Each event can be a 1 or 0 outcome.
I have a good reason to believe that the factors ...
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2answers
51 views
Hypergeometric Probability with a twist
A manufacture receives a lot of 200 parts from vendor. The lot will be unacceptable :
If more than five (>5) parts are defective.
The manufacturer will select randomly K parts from the lot ...
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1answer
18 views
How to decide sample size for validation?
I have data having over 20000 rows.
1) I am going to use a tool to test how many error rates this tool will calculate in this data.
2) And then, I will randomly choose some data and check how many ...
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2answers
79 views
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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9 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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1answer
69 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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0answers
28 views
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
37 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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2answers
55 views
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
29 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
44 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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0answers
26 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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0answers
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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0answers
19 views
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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0answers
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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16 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
33 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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49 views
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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0answers
22 views
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 ...
4
votes
2answers
160 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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0answers
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
41 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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0answers
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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0answers
61 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
146 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
51 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
55 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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0answers
33 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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0answers
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
193 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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0answers
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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0answers
165 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....
2
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1answer
38 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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0answers
22 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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0answers
20 views
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
53 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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0answers
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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
55 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 ...
