Statistical Analysis Stack Exchange
Statistical Analysis Stack Exchange

Questions tagged [population]

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

A population is the entire set of units from a group which is to be studied. Therefore the definition of a population depends on the actual research question. For instance, if the interest lies in estimating electricity consumption of U.S. households, it might be too costly and/or time-consuming to collect data for all households. For this reason we usually gather a (representative) sample of this population to draw inference. Imagine we had sampled all U.S. households, then we would have data on the entire population for our research question. If the question changes to "estimate the electricity consumption in North America", our previous population data becomes a sample data again.

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Why does a 95% Confidence Interval (CI) not imply a 95% chance of containing the mean?

It seems that through various related questions here, there is consensus that the "95%" part of what we call a "95% confidence interval" refers to the fact that if we were to exactly replicate our sampling and CI-computation procedures many times,…
Mike Lawrence
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Locating freely available data samples

I've been working on a new method for analyzing and parsing datasets to identify and isolate subgroups of a population without foreknowledge of any subgroup's characteristics. While the method works well enough with artificial data samples (i.e.…
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What is the difference between N and N-1 in calculating population variance?

I did not get the why there are N and N-1 while calculating population variance. When we use N and when we use N-1? Click here for a larger version It says that when population is very big there is no difference between N and N-1 but it does not…
ilhan
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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 million population to get an idea of how different…
Avrohom Yisroel
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Statistical inference when the sample "is" the population

Imagine you have to do reporting on the numbers of candidates who yearly take a given test. It seems rather difficult to infer the observed % of success, for instance, on a wider population due to the specifity of the target population. So you may…
pbneau
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What is the difference between a population and a sample?

What is the difference between a population and a sample? What common variables and statistics are used for each one, and how do those relate to each other?
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Statistical methods for data where only a minimum/maximum value is known

Is there a branch of statistics that deals with data for which exact values are not known, but for each individual, we know either a maximum or minimum bound to the value? I suspect that my problem stems largely from the fact that I am struggling to…
user2390246
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Why do we use term “population” instead of “Data-generating process”?

I have always been confused about the use of the term “population” in statistics. In my first statistics course I was taught that we need a sample, because surveying the whole population is too costly. So there is the whole population and there is…
Moysey Abramowitz
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Estimating population size from the frequency of sampled duplicates and uniques

There is a web service where I can request information about a random item. For every request each item has an equal chance of being returned. I can keep requesting items and record the number of duplicates and unique. How can I use this data to…
hoju
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Is any quantitative property of the population a "parameter"?

I'm relatively familiar with the distinction between the terms statistic and parameter. I see a statistic as the value obtained from applying a function to the sample data. However, most examples of parameters relate to defining a parametric…
Jeromy Anglim
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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?
Sophie Michel
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Is it appropriate to put "error bars" on data when you have the full population?

I have data on the large number of people who were applying to receive an award. Everyone who applied must fill out a survey and specify their gender (although they can choose "prefer not to say"). My question: is it appropriate to put "error…
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Male and Female Chess Players - Expected Discrepancies at Tails of Distributions

I'm interested in the findings of this paper from 2009: Why are (the best) women so good at chess? Participation rates and gender differences in intellectual domains This paper attempts to explain why the very best male chess players appear to be so…
tom
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Does it make sense to compute confidence intervals and to test hypotheses when data from whole population is available?

Does it make sense to compute confidence intervals and to test hypotheses when data from the whole population is available? In my opinion, the answer is no, since we can accurately compute the true values of the parameters. But then, what is the…
sitems
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Bias in average age for grandmaster title qualification by age groups?

It has been known for quite some time that the youngest age at which chess players managed to qualify for the grandmaster title has significantly decreased since the 1950s, and there are currently almost 30 players who became grandmaster before…
Tsundoku
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