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

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How much weight should be given to sample mean as an estimate of the population mean?

This R code creates a population of size 10,000 with a population mean of 3 and a population standard deviation of 2: population <- rnorm(10000, 3, 2) We can ...
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38 views

Forecasting - Population Death Rates

Wondering if you can help me out with this problem: I have 2 closed populations of products (call it Product X, and Product Y). Population Size of each product 10 million each (Product X = 10 ...
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12 views

Significance test for subset variation from population

I have customer churn data: independent features like customer gender, location, age etc. outcome feature representing whether he/she has churned or not My population churn rate is around 30% ...
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32 views

T-test for Bernoulli Distribution- Sample or Population data for SE calculation?

Am struggling to understand part of the answer to a question have done- Qu- In a given population, 11% of the likely voters are African American. A survey using a simple random sample of 600 landline ...
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5 views

Something confused about parent population and sample space

My text book proclaims that iff there is exact one element in each sample, then sample space is equivalent to parent population. And I think it's not correct. For example, let parent ...
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1answer
7 views

Comparing results of surveying two different groups (of the same size)

I have surveyed two groups of people. They had option of answering one of three questions. Both groups picked one of the answers around 50 and 51 percent of time. How do I compare if this difference ...
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5 views

Comparing a sample's mean to the population's mean from which it was taken

Let's say I had Population A (N=1200). Population A is composed of 1200 Sample areas each with their own mean/SD, etc. Let's us assume that taking all of these Samples together is the entire ...
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17 views

what's the right way to combine binomial parameter estimates?

let's say you have a bunch of weighted coins. by observing flips, you can estimate (a confidence interval for) the binomial parameter for each. how should you combine these to summarize the ...
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22 views

How do I calculate needed sample size

I am measuring visitors to a website in an A/B test (i.e. showing two different versions randomly to visitors and comparing what % converts). I am trying to calculate an estimate for what sample size ...
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36 views

WEKA accuracy confidence interval

I have a dataset consisting of thousands of companies from the UK. For 300 of these companies, I collected several indicators which were extracted from social media (e.g. #likes). I have built a model ...
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17 views

How can I compare data from a sample of a population with data of that population?

I am looking at a survey and I want to crosscheck the data from the survey respondents with the data from the actual population (we have the information available) to see whether any sub-groups were ...
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1answer
97 views

Defining a Population

I am tracking monthly data entry errors in a customer service dept. of 20 people, and then doing regression and correlation analysis on variables like typing speed and data entry error. I have data ...
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1answer
55 views

Estimating frequencies of a population

I have a sample of size 1121 from a population of size 2171 and I don't have access to any additional samples. The counts are ...
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12 views

Is using the whole population and sample data as a co-variance in spatial analysis correct?

I have two datasets that I am using to fit a spatial regression model. One is from the whole population (say means of bike usage in each state), and a sample population (statistics means of those with ...
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18 views

What kind of delimitations belong to population and sample respectively?

I'm writing a bachelor's thesis and the research question is "How ambitious is Sweden's electronic tax return system compared to other states'?". We wanted to investigate those states which (1) ...
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1answer
291 views

What is exactly distributed according to t-distribution?

I try to understand the idea behind the t-distribution. Here are the steps that I have understood so far: We use a sample of N elements to estimate the population mean. In more details, we use the ...
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1answer
159 views

How to extrapolate my sample results to population

We have tested randomly selected bacteria ($k = 198$) for antibiotic resistance over a period of 3 years (total isolates $n = 444$) and observed $117$ resistant strains. I would like to extrapolate ...
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3answers
106 views

How to compare percentages for populations of different sizes?

I have several populations (of people, actually) which vary in size (from 5 to 6000). I would like to visualize the ratio of women vs. men in each of them so that they can be compared. I will get, for ...
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2answers
75 views

Restoration of gender balance after wars - what principle underlies this?

I am wondering what is the statistical principle that underlies the following observation. After every war in history, the male population of a given region would severely decline, tipping the ...
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0answers
24 views

Using population as weights in regional-level data

I'm analyzing regional-level data (variously at the level of metro, micro, and county levels depending on their economic integration/population agglomeration). I'm using STATA 12 SE. It seems ...
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1answer
28 views

How to scale up mean/variance and confidence interval of clinical trial for whole population

In a clinical trial I have 1000 patients with disease A. Their mean treatment cost is 1000$ per patient with a 95% confidence interval of [900;1100] for example. The whole population of country X is ...
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20 views

How can test corpora (with different sizes) be compared to each other via accuracy?

I need an advice regarding a text-classifiction scenario. I use a simple accuracy measure defined as #(correctly classified classes in a corpus X) / #(all docs in X). Let A, B and C be three ...
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52 views

Choosing right test to compare two populations

I have two populations whose size is 36 and whose values I want to compare. Example ...
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10 views

Could someone verify this logic for managing probability distributions in experiment samples?

I'm not well versed in stats lingo, but am hoping my logic in the concepts here makes sense and is correct. Often in my work (measuring electrical responses of cells) I take of more than one ...
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2answers
62 views

Compare official population distribution with sample?

I have official numbers regarding the population of specific ZIP codes that belong to a certain region, e.g. 90210 has population of 20.000 (just an example). (The set of ZIPs comprises a city and its ...
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42 views

Has there been a spike in Germany's birth rate? [closed]

I hope this is on topic here... about 40 weeks ago Germany won the World Cup. At the time I thought there would be a noticeable jump in the Birth Rate there. I've been searching for current ...
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1answer
1k views

Advantages and disadvantages of using population and samples for statistics

I need to know the advantages and disadvantages of using a sample or a population to collect data. I understand what a sample is and what a population is, but I do not know what the advantages and ...
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16 views

Filling in “gaps” in Sample data from universal data

Quick background - I have a BS in mathematics, and have just recently started a position related to data science (nothing heavy, but requires enough simple statistical analysis that I find myself ...
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40 views

Rigorous definitions of sample and population

I am trying to understand some basic ideas of econometrics (and mathematical statistics) from the precise, mathematical point of view, avoiding vague explanations. I am beginning to learn about these ...
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31 views

Describing Differences between Two Inferred Populations

I am interested in the size of an animal in two populations, and found reliable estimates of the population provided by NOAA. The data was in the form of estimated total population within discrete ...
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7 views

Matching two populations that have different disease status that have undergone the same intervention?

If there are two populations, D+ and D-, where D is disease state, and both populations have undergone an intervention I, what would be the best way to design that study? Given that this is ...
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42 views

Comparing differences of ratios in 2 independent populations

I have a setting that I think is quite similar to the one described in What type of statistic should I use to compare ratios in my experiment?. I have two independent populations, which were screened ...
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16 views

Process interpretation of confidence intervals?

Frick (1998) explains how statistical inference can be interpreted as making causal claims about processes, without resorting to random sampling and infinite populations. This view seems particularly ...
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1answer
59 views

Confusion about the sample distribution.. Can you please enlighten me?

I thought that the sample distribution was an approximation of the distribution of the underlying phenomenon. But then the book says: We will denote the sample size by $n$ ($n \le N$) and the ...
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3answers
147 views

Why take multiple samples from a population?

I'm fairly new to Econometrics, and I'm curious about, when trying to estimate the population parameter, why it is important to take multiple samples of the population, instead of just combining all ...
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12 views

Confirm heterogeneity in a fish population over time

For my thesis I have to statistically prove that heterogeneity is establishing over time, more specific in the weights of a fish population. My dataset consists out of the weights of 17fish and the ...
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3answers
110 views

Standard error of a population

I measure the weight of 100 people and pick 20 lots of 5 people from these 100. Therefore n = 5, repeated 20 times. The 100 people represent the population and groups of 5 people represent samples ...
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1answer
20 views

Are daily updated data a sample or a population?

I want to do some tests based on all historical data of a product updated on a daily basis. These data are not supposed to have any time trend associated with them just be pulled on different days. I ...
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1answer
133 views

Standard Deviation of small population (less than 30)

Do we calculate the Standard Deviation of a population the same no matter how small (say less than 30) population size gets? Does distribution type play any roles in this? Thank you in advance
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1answer
93 views

Chi-square test on a sample from population having an unequal distribution

I got a sample with an unequal gender distribution ($30$ males to $200$ female). This distribution is quite "representative" for the population the sample is taken from. Nevertheless, in a paper, ...
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3answers
236 views

How can you tell if a yearly increase in population is statistically significant?

I have daily data for two years consisting of "number of sightings" each day. Is there a way for me to test whether the data for year 2 is "significantly" higher than the first year? I know the ...
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25 views

Testing if two population means are equal

In the situation where I have two estimated population means, and I want to see if they are equal, I compute $\frac{ \bar{y_1} - \bar{y_2} }{ se(\bar{y_1} - \bar{y_2}) }$ and compare to the ...
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49 views

Reducing the amount of data by extracting a representative sample of my population

I have 6 B&W images representing different wavelengths (i.e. Landsat bands) of the Alta Valtellina (Italy). I extracted from the images only the areas of bare soil. Now, I want to perform a PCA on ...
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81 views

How to determine an appropriate sample size for a normal distributed population?

I am trying to extract a sample from a given population. Assuming the population distribution is normal (I still have to test it, but I am confident it is), since the number of observations in the ...
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28 views

Compare variable in two independent samples

There is a hypothesis that in online health communities influential members (higher reputation) tend to post more emotional support than regular members. Emotionality of answers were determined by a ...
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2answers
66 views

sample versus population in experimental data

I am not statistically oriented, so I am hoping you might be able to help. I have a small lab setup that mimics a larger natural process (natural disaster). I have designed and completed 46 ...
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1answer
141 views

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 ...
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1answer
46 views

Can the population be smaller than the number of possible outcomes?

Say a random variable $X$ returns one of the values $1, 2, ..., 6$. Conceptually, does it make sense to speak of a population, where each individual element is just $1$? In other words, does the ...
2
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1answer
33 views

Why are estimation results sharply different from the actual population (exponential distr.)

For my work, I analyze the field failure data sometimes and make decisions accordingly. (spare parts quantity, optimum preventive replacement point, ...) I made an experiment in Excel. Using inverse ...
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1answer
57 views

How do I calculate required Sample Size to get useful confidence interval length for Bernoulli random variables?

I am pulling meta data fields from a population of 100M documents. These meta fields include things like Author Name, Author Location, Keywords, etc. Some documents have all of these meta fields, some ...