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

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Mixture distribution fitting for latent variable analysis

Are there any analytic approaches to using mixture distribution fitting for latent variable analysis? I'm specifically interested in existing approaches to determining whether mixture components ...
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11 views

Heterozygosity and the Wright-Fisher model

I was reading the textbook [Probability Models for DNA Sequence Evolution][1] by Durrett. In chapter 1, he discusses the Wright ...
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25 views

Assuming the true mean

I've collected fluorescence data from some bacterial cells. Each cell has a gene in it which can be induced to fluoresce. However, even without being induced, the gene will still fluoresce a little. ...
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20 views

Measure difference in answers on survey depending on item response options

For my thesis I sent out a questionnaire that has 10 questions. I set defaults: the first seven question had the default set to the desired answer and the last three questions had the default set to ...
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49 views

Interpreting coefficient errors in regression from uncertain population

I'm working on some regressions for UK cities and have a question about how to interpret regression coefficients. In a typical regression, one would be working with data from a sample and so the ...
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56 views

Difference of means when population mean is known?

I’ve approached a unique problem, and I want to make sure that I am going about the test that I am running in the correct way. Here’s a brief background: The goal of this project is to automate an ...
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44 views

Multicollinearity in a “population model”

I was talking with a colleague who told me that at the time of making logistic regression across a population did not have to worry about assumptions such as multicollinearity, because when analyzing ...
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20 views

Learning theory for search data?

Has learning theory ever been applied in practice for search log data? If so, what are some findings about generalization/learnability from this data? I'm interested in generalization about an ...
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58 views

Do you need to report the standard error of the mean when the sample is the population?

The other day, my tutor told me that whenever a mean value is reported, the standard error of the mean must be reported alongside. But surely this isn't always the case? For example, let's say we ...
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37 views

Is a sample of 1961 people out of a population of 225,000,000 a sample size that is too small? If so, why?

I am working by a set of problems on a single question in my textbook. The question explained that there was a recent survey of 1961 adults out of a population of 225,000,000 and asked me to construct ...
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8 views

Use of multiple regression for data on 20 countries representing nearly the whole population

I have operational expenditure data for 20 countries (representing 90% of the whole population) which I want to compare with other variables from the countries (e.g. GDP, Population etc). Do I still ...
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70 views

Interpolating time series

what are best ways to interpolate time series? I have three data points(1980, 1990 and 2001) and I need to interpolate them. Using R na.approx doesn't seem to be what I need since the data I need to ...
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39 views

appropriate hypothesis test for non-negative quantity

This question is intentionally written in a very abstract way, because I am interested in a generic solution, or for pointers to different possible concrete cases in different fields: I am measuring ...
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23 views

Predicting the missing data out of three values in each of the two vectors [duplicate]

I have 2 vectors of rural and urban populations of the same country. (years from 1975 to 2020) with only three values (1980, 1990 and 2001 years) in each. And I need to predict the missing data. My ...
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1answer
41 views

Is it true that values of parameters do not vary from sample to sample?

This is something I was told. However, it seems to me that parameters of a population can be functions of time, in certain situations, in which case the values of parameters could vary from sample ...
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5 views

How to identify a subset of effects as the drivers of significant differences?

Okay I will explain this as best as I can. I have an additive risk score for each of my observations (i.e. I'm putting 100 individual effects into a single variable). The means of this risk score ...
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48 views

Have population, use inferential statistics? Also, non-normal dependent variable, what to do?

Background: We are looking at parental leave in Iceland. We are particularly interested in whether the economic crisis and the resulting changes in parental leave legislation affected the time taken ...
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15 views

Augmented split plot experimental design

I planned a field experiment with different genotypes according to an augmented design (check repeated entries plus unrepeated entries). Since I am testing a segregating population, each plot split ...
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38 views

Random variables: True or False

I sometimes get confused when reading statistical definitions when they mention random variables (RV). Are they talking about a single draw? Are they talking about an estimator? To make things clear ...
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1answer
61 views

Sampling probability

Say I start off with N single cells in a sample. These are then allowed to grow untill there are x progeny from each individual cell. How many cells must I take so that I have at least one progeny ...
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1answer
115 views

How do I detect the number of distributions in a set of data?

I'm trying to detect subpopulations of data in a set of data. The problem is that the data may have more than one subpopulation and the subpopulations may not be normally distributed. For example, ...
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26 views

Finite Population Correction Factor

A simple random sample of 21 observations is drawn from a finite population of 41 individuals. If the population mean is 300 and the population variance is 7, then after applying the finite ...
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1answer
30 views

Question Regarding Statistically Significant Population Attributes

I have a problem I am trying to solve with the Chi Squared test, but I am starting to realize there are probably better methods to use, and I was looking for suggestions. Say I have two independent ...
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1answer
61 views

Spearman's rank correlation coefficient over population

I have a data set composed by 2.000.000 projects, each of them is defined by the number of active users and the size (KBs) of the project. I would like to check whether a correlation exists between ...
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24 views

Linear mixed model when interest is ONLY in population

Lets say we have 1 to 6 repeted measures over time for some (many) subjects, and the outcome is values between 0 and 23 (so we assume normal distribution). For a normal distribution the fixed effects ...
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65 views

How is this version of the pearson correlation coefficient derived?

After taking my first semester stats class I started getting more and more into statistics. Currently I've come across this version of the Pearson Correlation Coefficient. Comparing this formula to ...
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44 views

Comparing a subset of a population with the entire population?

Is it possible to compare and test actual subsets of a population to the entire actual population? That is, let's say for a baseball team we want to know which players are contributing to the team's ...
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1answer
59 views

What are the consequences of knowing (or not knowing) the range of possible answers from a test

Lets say we are interested in some unknown variable x. We poll a x at different intervals and get a set of values that x has been. However we know that if we poll x enough times we will eventually get ...
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34 views

What benefit can be gained from finding total population size

I would imagine this has been asked before but I can't find it so feel free to link if you can! Lets say I have a sample size of 100 and an unknown population size. There's a great deal I can learn ...
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38 views

$R^2$ in multivariate regression

I'm trying to determine how the population $R^2$ value is defined in the multivariate regression model where we have $Y_i = \mu_y + B^\prime(X_i - \mu_x) + err$ Where $Y_i \in \mathbb{R}^q$ and ...
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1answer
68 views

What does the “different populations” result of a significant group t-test mean exactly?

Why does finding a significant difference on a given measure, say mathematical ability, between two groups (e.g., via an independent samples t-test) have to be equivalent to the two groups coming from ...
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2answers
162 views

Z-scores, standardized tests and population means

I have been using z-scores by subtracting the mean (and then dividing by the SD) of the sample, whereas I recently read they actually need to be the population mean and SD. Assuming you are ...
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1answer
50 views

What is the Australian Calculator?

i need to know how to use the Australian Calculator to get my sample size. i was instructed to carry out my research using the Australian Calculator, but i don't know what it means.
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17 views

Sample/Null Value

I was running through question section on my stat book and the following question was posed: If our sample value is close to the null/population value, we conclude that ... I don't get if that ...
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61 views

How useful are per capita calculations in level of education of a population?

I had a discussion recently in which it was stated that Scotland having more universities in the top 200 per capita than any other country is a good indication of the intelligence of the population of ...
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1answer
40 views

Is my data representative of Bristol?

I've got some data about people in Bristol. I have about 75,000 records. Part of my dataset is each respondants age. Aside from this, I have also downloaded census data for Bristol, which gives me ...
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71 views

To know clearly about the population

What is the difference among target population,study population and theoretical population ?
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66 views

Why is 30 touted as a sample size when the tables say otherwise?

If I have a population of 5000, statistics suggests that I need to sample about 350+ to get a confidence interval of 95% with margin of error 5%. So why do I see that sometimes we can get away with ...
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43 views

Finding overlap in two similar populations

I run a few different projects throughout India and want to understand how many unique individuals I've provided services to total. I don't collect names or unique identifiers, so all I know is a) the ...
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112 views

Whether the population exists in an experimental study?

In my oral exam one of my teachers asked whether the population exists in an experimental study. I answered: "Yes. the population exists in an ...
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1answer
52 views

What test of significance should I use to analyse visits to a clinic by various groups?

Apologies for the noob question. After a day on Google and Wikipedia I still can't quite work out what to do. So here I am. A small private healthcare clinic in the UK has asked me to look at their ...
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1answer
114 views

Interaction variables work differently when population is split

Let's say I have two predictors to predict financial risk: Gender and shopping habits. Gender has levels of "Male" and "Female", while shopping habits has "quick shopper" and "slow shopper". I am ...
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1answer
126 views

How to compare sampled areas to the Census?

I would like to discriminate sampled areas that are representative or not representative of their corresponding population, for a given characteristic. Suppose I have surveyed areas (i.e. Census ...
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23 views

What are appropriate statistical test to compare historic Census variables for different locations?

I am wondering if anyone has suggestions on which statistical test would be appropriate to compare demographic data obtained from 1900 Census schedule sheets? I have a database of boarding school ...
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19 views

Applying the distribution of a large sample to estimate probability for a smaller sample

I have the sample size, mean and standard deviation for the number of births per year for my county, but I'd like to transfer that information to a smaller population within the county (ie. a school ...
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84 views

Testing to see if a population is normal?

I'm an amateur statistician. I do it mostly for fun. I'm finishing up on my first semester stats class that covers up to hypothesis testing. I'm planning on beginning learning simple regression ...
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2answers
64 views

Sampling from a dynamic population

I need to create a sample of a given size from a population. However, the population is dynamic, that is, comes as a stream of items, and every item has a "time stamp" based on its location in this ...
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1answer
75 views

Why describe a sample as i.i.d.?

I’m hoping for some help understanding the concept of RVs with respect to their use in the theory of drawing inferences on a population from a sample. To draw inferences on a population using a ...
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63 views

Need to verify sample is representative of known population of animals

I'm a biologist trying to verify that the age, gender, and family group of my samples from a population of whales is representative of the population, in order to make inferences in the discussion. ...
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1answer
54 views

For a research project I'm trying to estimate how many videos currently exist on Youtube

Official stats on how many videos (rather than how many hours or what volume of data) seem quite hard to come by. My current idea is something like this: A youtube URL is like: ...