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Questions tagged [sample-size]

This tag is very ambiguous. Use it when the question is about sample size and NONE of the following are more appropriate: [small-sample], [large-data], [power-analysis], [power], [underdetermined] or [unbalanced-classes].

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1answer
11 views

Comparing data sets of varying sizes

Suppose I want to compare the similarity of 2 data sample sets (a and b). Data set a has 13 data points and data set b has 1000 data points. For each data set, I compute a metric z (like the mean). ...
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2answers
74 views

Can bootstrapping improve the test power, when the sample size is small? [on hold]

When the sample is small and study is under-powered, can bootstrapping be used to generate data and increase the sample size (and improve the test power)? Is there any way that bootstrapping can be ...
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0answers
9 views

Minimum Sample Size for M&A Event Study

as statistics beginner I was hoping you could help me with regards to the following problem: I wanna conduct an event study (analysing abnormal returns of share prices) to derive performance effects ...
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0answers
15 views

Relative and Absolute Precision in Sample Size calculation [on hold]

Can someone give me a tip on how to calculate precision? There isn't a lot of wisdom here so I apologize in advance for the wording... Its an energy savings application where based on a months data (...
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0answers
9 views

Combined Variance of two groups with different sample sizes [duplicate]

I have the mean and standard deviation for Male and Female groups in a study, I'm trying to get the combined mean and standard deviation. The two groups have different N's. I can get the weighted ...
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0answers
14 views

Determining sample size of a Gaussian subset with new std

I have N1 samples that is distributed close enough to Gaussian with 0 mean and std1. For simplicity, we can assume N1=1000 and std1 = 7. Now I want to choose a subset of those samples that is ...
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1answer
22 views

Effect sizes independent of sample size

So I have a small sample size (N=24) but found an extremely large effect size for an effect. A common phrase appearing is 'effect size is independent of sample size,' which I had taken to suggest ...
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0answers
33 views

Calculating sample size for a stratified random sample

I have a total population of 4,000 farmers, divided into three unique regions. Approximately 50% of the farmers live in Region A (N=2,000), 27% in Region B (N=1,080), and 23% in Region C (N=920). I am ...
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1answer
13 views

Does an interim sample size re-estimation increase type 1 error if based on the overall event rate?

Suppose that a sample size is to be calculated for a trial: a presumed effect size summarizes the effect of intervention (relative risk RR $\exp(\theta_1)$), and background gives the rate of events in ...
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0answers
14 views

Minimum sample size calculation a posteriori

I am running a number of experiments where I obtain a large number of observations with one variable (yielding two sets of values; many more than would be needed for a hypothesis test). I want to test ...
0
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1answer
29 views

Least squares regression coefficient with minimal information

If I only have a correlation matrix of 4 variables and the sample size, is it possible to predict 1 variables from the other 3 while using information about sample size? I’m trying to use lm but my ...
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0answers
14 views

Can I draw a histogram of the mean sample distribution (n=30) sampling from my dataset (n=200)?

I would like to test whether my data reasonably satisfies the normality assumption necessary to apply a t-test. My understanding is that, to apply a t-test, the distribution itself does not need to ...
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1answer
24 views

Sample size needed to prove equal proportions

We are trying to prove that three groups have the same proportion of some effect. We are struggling with formulating the null hypothesis, and whether or not the sample size is big enough. The ...
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0answers
29 views

Calculating sample size for one 5-point likert item

I am trying to calculate the optimal sample size for a hypothetical experiment with the following: Treatment condition (n TBD) Control condition (n TBD) My dependent variable is an 'intent score' ...
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1answer
55 views

A question about hypothesis testing [closed]

Question I am actually finding no clue how to start with this sum. Please help. Thank you.
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0answers
14 views

Web Based Survey Sampling method

I am doing a web based research with target audience as general public. I am a student and so due to limited resource, i basically did snowball sampling. I approached all those whom i knew, some ...
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0answers
19 views

A/B testing formula: How to calculate the necessary sample size to run an A/B test?

I heard there is a formula to estimate the sample size when running an A/B test, using the following: . significance level . power . expected standard deviation of the change in the metric we are ...
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0answers
16 views

A question on realizable sample complexity

I came across the following exercise, and I just can't seem to crack it: Let $l$ be some loss function such that $l \leq 1$. Let $H$ be some hypothesis class, and let $A$ be a learning algorithm. ...
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0answers
24 views

Sample size equation based on clinical paper

Hoping this one is easy, but I've been struggling to try to find what approach is being used online. I'm trying to replicate the powering of a clinical trial for research purposes based on the below ...
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0answers
37 views

Sample size calculation in repeated measures design for linear mixed models

Does anyone know a method how to calculate the required sample size in a repeated measures design that will be analysed using linear mixed modelling? The design looks as follows:I have two groups (...
2
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2answers
64 views

Sample size question (small vs large)

I have a question about sample sizes. I have a data set in which I have following conditions: 1) Day 1: Total=3500, Fail=200;Fail%=6 2) Day 2: Total=6700, Fail=340, Fail%=5 3) Day 3: Total=1100, ...
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0answers
20 views

Plot for sample size/Power according to ranges of effects estimation for Logistic Regression Mixed Model

I am a junior statistician and naïve in sample size estimations and I have to make a plot in which the power and sample size could be estimated according to different effects (OR or beta). My model ...
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0answers
13 views

Power Analysis for Case Control Regression?

If we conduct a case control study and plan to analyze the results with multiple linear regression, which power analysis should be conducted to select sample size? There are separate calculators for ...
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1answer
20 views

What are p and p0 in ICC.Sample.Size

The purpose of this R package should be self-explanatory. However, its parameters are not. The help page never explains what is meant by p and ...
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0answers
10 views

Location level a/b testing sample size

We are setting up experiments to measure impact on the city level. Customer in certain cities are treated and we have list of holdout cities with similar behavior. Measurement of lift of the ...
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4answers
66 views

How Confident Should I be

I have a question about confidence in a conversion rate. I have a sales page that had 1382 visitors, and 23 of them purchased the product. I know for that sample I had a 1.66% conversion rate. But ...
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0answers
59 views

Win probability of a game character vs. two other characters

Clarification about original problem: Dota 2 is played in matches between two teams of five players—known as the Radiant and Dire—, with each team occupying and defending their own separate base ...
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0answers
22 views

Sample size formulae

In order to calculate sample size for hypothesis testing, we consider level of significance and power. For level of significance, two sided values ($Z_{\alpha/2}$) are taken into account, but for ...
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0answers
19 views

Power calculations for moderator analyses in RCT

I am running a randomised controlled trial of a savings intervention in India whereby randomisation is at the individual level (not clusters). In my power calculations, I also want to factor in a ...
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1answer
21 views

consistency of an estimator in real data

as we know in statistics we are interested in the properties of an estimator , as my estimator is consistent , in probability sense it can be shown as $P(|estimator - true| <- positive) = 1$ as ...
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0answers
29 views

Effective Sample Size for Weighted Samples

I have an MCMC sampler with weighted samples and I want to compute effective sample size at every step to determine sample degeneracy. I am using the following formula: $ESS = \frac{(\sum_{i=1}^N{w_i}...
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1answer
19 views

Sample size needed?

I need some help calculating the minimum sample size needed for my upcoming trial. I’m doing higher degree research on eHealth, so I have little knowledge about statistics and sample size calculation. ...
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0answers
26 views

Statistically determining the median of a data set via quantiles of a sample

I was thinking of algorithms for statistically determining the median of a large data set. To estimate the complexity of my idea I need the following Probability: I have a dataset $\left\{x_i \right\}...
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0answers
19 views

proper sample size for the central limit theorem to hold

I have tested the central limit theorem with 1000 samples and a sample size of 4. The resulting distribution was nowhere near normal, and when I used n = 30, it did start looking normal. Is there a ...
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0answers
8 views

Estimating Effective Sample Size in Unequal clustered design (ratio-type estimator)

I'm having trouble understanding how these experimenters calculated their effective sample size. The free article is located in this link here: https://academic.oup.com/icesjms/article/60/2/297/...
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0answers
21 views

Sample size for AUC based on mean and SD of raw data

I'm trying to estimate the sample size required to achieve 80% power at a 5% significance level for a superiority study comparing AUC from bioavailability data. My challenge is the only previous ...
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0answers
9 views

Hypothetical sample size

I have a data set of n=98 of values that is normal distributed. This data set has a certain spread and hence a certain standard error of the mean. I now want to test how many samples (ns) I would need ...
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0answers
12 views

Simple sample size calculation for partial correlation?

I am probably missing something but I need to find the appropriate "steps" to use with G*Power to do a power/sample size calculation for a partial correlation. Correlation between two variables ...
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0answers
24 views

How can I find required sample size to meet certain condition in R?

I need to find the required sample size to meet certain condition in R. The question where I need help is posted below. Suppose a forester would like the sample mean to be within 1 square inch of the ...
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1answer
22 views

Help with psychological research for my dissertation?

1) Is median split effective to divide participants in 2 groups considering their scores on a scale? I am using PECK scale (Personal experience checlist) and i need to divide participants into minimum ...
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0answers
21 views

ANN webpage classification based on visual segmentation: sample size and parameterization

I am trying to classify web-pages based on their visual layout. My application visits a categorized webpage, catches certain elements' bounding boxes (rect in web-element term) and label them. Label ...
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1answer
54 views

How can I calculate power for a conditional logistic regression?

A client wants to perform a 1:1 matched case control study, matching on 3 risk factors, and analyze results using conditional logistic regression. A sample size calculation is required in order to ...
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0answers
22 views

comparing sensitivities

We want to compare two sampling methods. All patients will go through a DNA test for diagnosis(positive or negative). Then samples are taken to identify the determine the type of bacteria and ...
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2answers
42 views

Estimating sample size en poussant

If we have sample mean of $n$ observations as $\bar{x}$. It is given that maximum value of the whole set is $M$ and minimum value is $0$. How many more observations we need so that the estimate for ...
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0answers
29 views

the power and sample size of one Poisson mean test

I was using the softeware PASS to calculate the sample size and power of a one Poisson mean problem. Solve For ................................................ Power Ha (Alternative Hypothesis).........
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1answer
22 views

Relationship Between Required Sample Size and Number of Predictors in the Model

Is it true to say that, in (logistic) regression, the required sample size to detect a given effect size for a single predictor increases with the total number of predictors included in the regression ...
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2answers
162 views

Minimum sample size per cluster in a random effect model

Is there a rational for the number of observations per cluster in a random effect model? I have a sample size of 1,500 with 700 clusters modeled as exchangeable random effect. I have the option to ...
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0answers
48 views

How is correlation among repeated measures calculated for ANOVA interaction effect?

I am performing a replication study, of an interaction effect found in repeated measures ANOVA. The study is of a 2X2 design (1 group of subjects, 4 measurements each). To estimate the required ...
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1answer
44 views

How to approach a classification problem when the sample size is only about 50

I was given a data consists of 53 people and I was asked to come up with a general classification rule based on biomarkers that can be used to classify each person under one of the three possible ...
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0answers
11 views

Type I and II errors accounted for by one equation?

On this website: https://clincalc.com/stats/samplesize.aspx both type I and II errors are accounted for by the one equation. Surely, because a type I error involves too much positive variance and a ...