# Tagged Questions

This tag is very ambiguous. Use it when the question is about sample size & the following are NOT more appropriate: [small-sample], [large-data], [power-analysis], [power], or [underdetermined].

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### Standard deviation of sample mean - unknown equation answered

Does anyone recognize mathematically or statistically what this formula's purpose is. If it is not statistically useful what does dividing a value by a constant and taking a square root mean? For ...
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### Jeffreys Interval Calculations and Sample Size

I have a rough understanding of bayesian statistics and of the Jeffrey's Interval/priors. I understand that the Jeffrey's interval takes the form: $$p\mid x \sim \mathrm{Beta}(x + 0.5, n - x + 0.5)$$ ...
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### Sample size determination for estimating a count

I want to estimate a simple variable: "**how many times my website is visited in 2015?". Suppose that I cannot count all visits to my website (it is expensive!), but I can count the connections on ...
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### Sample Size Calculation Using Wilson Score

I am using a number of different sample size methods to compare their usefulness for a particular study. One of these is the Wilson Score Method. I am searching for a table or chart of the sample size ...
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### Correlation analysis with simulation

I need to determine if two variables are correlated (have a relationship between each other). Issue 1: both variables take on values greater than O, in which, I can not assume normally distributed. ...
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### sample size for longitudinal quasi-experimental evaluation

I am working on the evaluation of a proyect designed to help crime victims to overcome their experiences. My main hypothesis is that the program prevent these victims being crime victims again. Since ...
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### Why would you want a smaller critical region when testing large samples?

Is it because when you have a smaller critical region you have a smaller probability of the event happening?
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### Calculating sample size for two-way ANOVA given effect size

I have an experiment with two groups and three timepoints (different subjects for each timepoint, so no repeated measures), and I understand a two-way ANOVA would apply to this situation. I'm trying ...
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### From successive samples of increasing size how do I measure “variability is within the error band” for a particular confidence level?

In the section 5.6 of book Data Preparation for Data Mining, by Dorian Pyle it states This is a complex subject, and it is easy to confuse what actually has been captured here. In the example ...
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### Sample size calculation

Medical student doing his first research here. This is a randomized controlled trial. Basically the study compares the effectiveness of skin glue over skin sutures. Since the length of each scar will ...
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### Sample size for correlation study if r=0.39?

I am doing a correlation study. I need help in computing the sample size given the correlation coefficient of 0.39 with a power of 0.80 and alpha of 0.05? Thank you and hoping for answers.
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### Multiple imputation: How many subjects per variable are needed?

I want to perform a multiple imputation via the mice package in R. My dataset looks as follows: 250 observations 60 variables variable type: numeric approximately 7-10% missings per variable ...
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### Sample size choice with binary outcome

Our civic association is planning to implement a survey asking our neighborhood one true false question. I would like to make sure that we obtain an adequate sample size. Let's assume N = 2500 ...
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### Population Proportion Confidence Interval

Looking at the equations for confidence interval and sample size estimation of population proportion, I don't understand why population size isn't a factor. Can anyone explain? I can't find any ...
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### sample size to estimate mean of zero modified log normal variable

I would like to estimate the average value of a variable "A" in a population. I think only 5% of the population has a figure of A > 0, 95% has A = 0. Using a previous non random sample, I believe the ...