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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How do I calculate the sample size required for a crossover AB|BA study?

I would like to know whether it is feasible to conduct this study. We have a subset of people in facility A (n=1300 per year), of which a proportion of these present a condition (n=18). Similarly, we ...
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2 views

Hilog-linear analysis for Categorical data

I found myself in a statistical predicament, and received a few suggestions from friends that didn't convince me a lot. I'm looking for advice on this predicament. I'd really appreciate it in advance. ...
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20 views

Sample size for tracking data

I'm currently trying to figure out how to estimate a fitting sample size for a specific problem. The situation is as follows: We've got x people, of whom we are able to track y% - all the time, so we ...
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1answer
39 views

Calculating Sample Size for Non-Inferiority Test in Cox Proportional Hazards Regression With Stratification

I have a binary predictor, X, in a Cox proportional hazards regression model, and I want to show that it is NOT a significant predictor. In other words, I want to show that there is not a significant ...
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1answer
35 views

How to calculate a sample size for validating correct/incorrectness of records in a data table?

I have read through existing answers on CrossValidated (plus elsewhere online) and can't find what I'm looking for, but do please point me to existing sources if I've missed them. Let's say I have a ...
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0answers
20 views

which method should i use for determining sample size?

what is the difference between the sample size determination method of using the critical values of the normal distribution with that of using the t-distribution? as an example if replication level ...
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1answer
17 views

Sample size for group comparison

I am collecting data from 3 different population groups (islands) and within each, comparing children from class 1 from 10-14 schools between two groups - those who completed kindergarten, those who ...
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1answer
35 views

must be a representative sample to apply factor analysis?

To apply the exploratory or confirmatory factor analysis, is what we should select a representative sample? And is there any condition to select this sample? I would validate a translated ...
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26 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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1answer
48 views

How to make sample space of the following question

My teacher gave me a question to solve.In the book of Ronald E. Walpole (Probability and Statistics for Engineers and Scientists), chapter no#3 exercise 1,question #2 which is as below: 3.2) An ...
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0answers
5 views

Accuracy results on subsamples

Given a binary classification task, let us suppose that a classifier achieves an accuracy result of $x\%$ on a sample of size $N$. What would be a way to calculate the conditional probability that ...
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24 views

Finding a confidence interval for observations being outliers

Suppose I have a sample with sample size $N$ that is obtained experimentally, e.g. I have counted the number of birds at a certain location at a certain time. Now suppose that the sample (the number ...
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9 views

Calculating sample size for a composite endpoint

I am trying to figure out how to calculate sample size for a composite endpoint. Say I have two groups, group A and B, and I want to know how they do after taking two different medications (let's ...
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0answers
17 views

Probability of taking a random sample of 24 measurements and getting a mean of at least 103.6 of true population

A random sample of size n = 24 measurements is drawn from a normal population. The sample has a mean of 103.6 and a standard deviation of 12.5. If the true population is 100, find the probability of ...
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33 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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0answers
13 views

How many data points per timeframe needed to calculate a meaningful rate?

I'm generating about 1.5 billion data points per month over ca. 6 million subjects. I have no data about the distribution but I know that some subjects generating millions of data point and other ...
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0answers
51 views

Model selection

I have a small dataset of 37 observations with students' performance on both cognitive tests (5) and professional tests (6). My goal is to predict professional tests (DV) with cognitive tests(IV). To ...
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0answers
17 views

How do I determine the minimum sample size needed to evaluate the performance of a binary classifier with a statistically significant result?

I’m trying to determine the minimum sample size(s) needed to evaluate the performance of a binary classifier with a statistically significant result. I'm not trying to compare different classifiers ...
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0answers
16 views

Bootstrapping Data from Multiple Sources

Sorry for any wrong use terms since I am not a statistician. I was asked to build a grand distribution based on literature identified data (6 in total). However, ...
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15 views

Sample calculation

I'm about to start an In vitro model experiment. I will have 3 groups to compare between them with continuous variables. I will use ANOVA for the comparison and I would like alpha to be 0.05 with ...
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0answers
13 views

Kruskal Wallis Test: Sample Size Difference

I would like to run a Kruskal Wallis test. There are 5 groups that I need to compare. ...
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0answers
23 views

Sampling size determination for small probabilities

I am not sure I could find a clear answer on a correct formula for sampling size determination for finding rare events. Specifically I need to be 99% sure, that failure rate of certain population is ...
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0answers
18 views

How is the sample size for a given population determined?

The following passage is an excerpt from Thinking, Fast and Slow by Daniel Kahnemann The risk of error can be estimated for any given sample size by a fairly simple procedure. Traditionally, ...
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1answer
36 views

Computing sample sizes from confidence intervals around Cohen's d

Is there a way how to compute sample size from Cohen's d and 95% confidence intervals (it's useful for instance for getting sample sizes from forest plots)? From How do you calculate confidence ...
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13 views

Minimal sample size needed univariate regression

Setup: I need to figure out how many years of data I need for $\beta_1- H_0$ to be significant at the 5% level. My plan as of now is to collect info on $y_{i1}, y_{i2},x_{i1},x_{i2}$ and run the ...
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2answers
52 views

Sample size calculation for proportion

I am in a doubt about using Absolute and Relative precision for sample size calculations. Suppose if I want to conduct a study to asses the prevalence of Hypertension in a general population, which ...
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1answer
30 views

Can I add more cases and/or predictors to existing set of data?

If I have a set of data with 40 cases and 3 predictors can I add more cases and/or predictors later to the existing set of cases if I want to explore the effect of more possible predictors? The data ...
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47 views

Sample size for logistic regression. How to determine the number need for positive and negative cases?

I would like to apply logistic regression for my research. And before that, I want to calculate the minimum number of sample size, positive cases, and negative cases. ...
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22 views

Sample Size Stumped

I am trying to come up with the best sample size for a QA problem. We are trying to make sure our product stays below a certain threshold. We make 600K products each day and each sampled product is ...
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1answer
41 views

cross validation vs. sample size

I am interested in performing GLM regression on a data with sample size of 37. After splitting the data into training (30 obs.) and testing (7 obs.) sets, I'm wondering wether it's better to build one ...
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1answer
22 views

Sample size calculation for the comparison of the means of three groups

I have to calculate the sample size for my project. The study is a comparison between three different treatments at three different time points. The outcome variable takes continuous values. We ...
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0answers
20 views

Sample Size calculation - Find minimum sample size to determine positive effect

I'm calculating the sample size required for an experiment with continous outcome variable. I'm considering two ways to calculate the sample size. One is based on a differences in 2 means test. The ...
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0answers
40 views

Sample size calculation - Pros and cons of using one-sided z-test over two-sample differences in means approach?

I'm calculating the sample size required for an experiment with continous outcome variable. I'm considering two ways to calculate the sample size. One is based on a differences in 2 means test. The ...
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0answers
30 views

Minimizing 95% Confidence interval extent for bootstrapped confidence intervals

I'm new to CrossValidated so please excuse any shortcomings in my question. Suppose I have a sample of 500, for a population of 500,000. I asked my sample of 500 what day of the week they go grocery ...
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1answer
32 views

IBM SPSS QUESTION: Measure the perception of the respondents

My problem to solve with IBM SPSS is: I have got answers to a question about X topic that contains 15 options of multiple response and I want to characterize the perception of the correspondents ...
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21 views

Selection model with cross-sectional data(limited sample), make any sense?

To my understand, when someone using the selection model, he make sense just when he properly mimic agent's choice behavior using agent's current characteristics, even in a reduced form. It's not a ...
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0answers
41 views

Using G*Power to determine the sample size for an repeated measures ANOVA

I am currently designing an experiment that I want to analyze using an RM ANOVA. Since some of the factors are confounded I need to do multiple ANOVAS. One analysis will be for 2x2 factors (within ...
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2answers
82 views

Statistical significance versus sample size [duplicate]

Statistical significance of a (variable in a) model grows with sample size. Citing Gilbert (1986): If one uses test statistics with constant size (i.e. a constant degree of confidence), almost any ...
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1answer
15 views

How do you develop Confidence Intervals based on non average data

I am collecting votes from an election poll. The rules for voting allows the voter to select ten out of 36 candidates for election. Any candidate whom receives at least 75% of the vote or more wins ...
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15 views

Does minimum variance imply a maximum for ess?

Does minimum of variance of weights $$ \text{var}(x) = \frac{1}{n} \sum_{i }^n {x_i}^2 - \frac{1}{n^2} \left({\sum_{i }^n {x_i}}\right)^2 $$ imply the maximum of Kish's approximate formula for ...
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1answer
29 views

Calculate sample size to determine freedom of disease with two level clustering

I'm trying to find a calculation that will allow me to calculate both: the number of farms and the number of sheep per farm I would need to sample to determine the absence of a disease for the ...
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0answers
17 views

How many samples is needed

I have a function (F) with n parameters (x1,x2,...xn) all the parameters are defined by normal distributions. I would like to know how many times I should sample F to get a reliable distribution. ...
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1answer
27 views

Sample size calculation for clinical trial

I am facing a problem regarding sample size calculation of clinical trial. Currently a drug is used at 2.5 mg for adult and ...
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0answers
18 views

Measuring “almost the same” when significantly different

The following table is of UK domiciled university applicants to UK universities in $2013$ and of acceptances, grouped by self-declared disability. A $\chi^2$ test on the numbers shows an extremely ...
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2answers
151 views

Mann-Whitney U test with unequal group sizes and one group very small

I have a sample of 24 participants who gave their responses to 8 questions. I calculated their mean response. Can I use Mann Whitney to compare between 2 groups where one of them has only 2 ...
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1answer
8 views

Difference in confidence intervals of two sample sizes given a finite population

I can't seem to wrap my head around this problem. My company is commissioning a facility that recovers two types of metal from ash generated from an incinerator: ferrous (metal containing iron) and ...
2
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0answers
60 views

Sample size needed to estimate probability of “success” in Bernoulli trial

Suppose a game offers an event which upon completion, either gives a reward, or gives nothing. The exact mechanism for determining whether the reward is given is unknown, but I assume a random number ...
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0answers
21 views

statistical signficance and sample size

I have a question regarding statistical significance and sample size for a website a/b test. using a sample calculator and knowing my control's conversion rate, 80% statistical power and a minimum ...
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33 views

Number of experiments when expected value = probability [closed]

How many times I should conduct experiment to have expected value which will be within some interval (for example 2 SE) of probability. For example how many times I should toss coin so that frequency ...
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3answers
398 views

Why is type I error not affected by different sample size - hypothesis testing? [duplicate]

I don't understand why the probability of getting a type I error when performing a hypothesis test, isn't affected. Increasing $n$ $\Rightarrow$ decreases standard deviation $\Rightarrow$ make the ...