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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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sample size to detect variability in a sample

I have a sample of continuous data which I use to build a random forest model. Now I want to determine, how many additional samples I would need to improve the prediction (reduce the RMSE by a certain ...
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1answer
21 views

Calculating Sample Size As Number of Days Needed For Significance?

I am trying to determine required number of days required to reach a significant result for a one-tailed independent sample test. I have sales data by day for my test and control group. The results ...
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0answers
7 views

Power of Tests for Proportions: One Proportion vs. Two Proportions

I am trying to calculate the required sample size for a trial, where my outcome is proportions (for each subject I am measuring if the subject had an event or not). I tried two ways and got different ...
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0answers
16 views

Testing if number of observations in experimental conditions is statisically different

I was conducting in experiment in which i sold products on a pay-what-you-want basis in 4 different information conditions. Apart from comparing the average willingness to pay across the 4 different ...
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0answers
18 views

How to compromise between using a lagged dependent variable and observation loss

I am working with panel data of several thousand observations in five time periods. As I have a strong reason to believe that past values of the dependent variable (DV) affect subsequent values of the ...
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1answer
14 views

How to compare coexpression networks from two conditions with different sample sizes [closed]

I have gene expression data from two conditions having different sample sizes i.e 8 and 32. I want to build a correlation among all genes (for both conditions) for comparison. So, I used "psych" ...
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1answer
16 views

Sample size for proportions and fisher exact test

I need some clarification. I am doing a chart review. Plan to test significance with fisher exact as its two interventions, one yes/no outcome. Presumed prevalence in the population is 15%, but ...
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2answers
32 views

What exactly is the sample size of an investigation?

My understanding of sample size is that it is a portion of the population that serves to represent the population. However, I'm not sure if the sample size of an investigation to investigate how X ...
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1answer
22 views

What is the sample size formula which i could possibly get minimum value in-vivo studies?

I am an undergraduate students who is struggling on how to do in vivo studies with my low budget. Therefore, I ask some help of you just in case you know about what sample size formula that I could ...
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1answer
22 views

Sample Size Experiment Proportion Failure

I have N machines and I want to implement an experiment E in them in order to improve their proportion of failures. However, I’m not sure yet if this experiment E will increase, decrease or do ...
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0answers
10 views

Sample Size Proportion Comparison Test Finite Population

How can I calculate sample sizes for a Prorportion Comparison Teste of Finite Populations? Is there a function in R? Basically, I want to know what is the finite population version formula for the ...
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0answers
11 views

Sample size calculation and number of independent variables for repeated measures Generalized Estimating Equations

I'm trying to understand sample size estimates for repeated measures Generalized Estimating Equations. Reading papers on this topic, it seems that the number of independent variables are not assumed ...
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1answer
16 views

Is survey response number big enough

This is a fictional example to demonstrate my question I'm trying to figure out at work. I sent out surveys to all organizations of a specific type in the US asking them what is the average time it ...
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0answers
12 views

How to infer the distribution of a statistic (Bayesian inference?)

I have a list of approximately 30,000 venues in a major US city. These venues hold all kinds of events, sports, conferences, concerts etc. I want to know the distribution of the 'capacity' of these ...
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1answer
18 views

Resource for an explanation of Sample size calculation when $\alpha$, Power and Effect Size for t-Test are given

For a simple z-Test or t-Test (one-sample or two-independent-sample with $n_1 = n_2$ and equal variance) I want to calculate the required sample size $n$ when the significance level $\alpha$, power ...
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1answer
12 views

Do ANOVA & MANOVA require balanced levels?

I have one independent variable with two levels, or categories, and four dependent variables. When doing a MANOVA or ANOVA test, how important is it for the number of observations in each category to ...
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1answer
20 views

sample size calculation in 3-arm survival analysis

In a 3-arms clinical trial, with time to event data, either A is superior to C or B is superior to C it will be considered significant. No need to compare A and B. I know how to calculate the sample ...
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1answer
25 views

In a meta-analysis, do you report the full N of each study or just the experimental n?

I just noticed that one meta-analysis (Jeon & Day, 2016) reported only the size of the experimental group. For example, when I look at the particular N sizes for the Robb & Kano (2013) studies,...
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1answer
22 views

What is necessary sample size for B in A/B test with unequal sample sizes?

I have a situation in which I want to measure if the error rate in system B (test) is worse than the error rate in system A (control). System A has a sample size of 100 and that cannot be modified. So ...
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1answer
14 views

Logistic regression: Sample size for emmeans comparisons

I conducted a logistic regression with a 3-levels categorical predictor in SPSS using the GENLIN procedure. As I am interested in the pairwise comparisons between all three predictor levels, I used ...
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0answers
15 views

What is the best hypothesis test method for a small sample size?

i am somewhat confused on how to proceed with the hypothesis testing, i have 1 sample with a total of 31 inputs divided into 2 groups of different conditions, 1 sample has 16 inputs, the other has 15. ...
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1answer
61 views

estimate confidence interval of empirical percentile [duplicate]

Suppose $n$ samples are generated from an unknown distributions and the empirical percentile is estimated. In python: ...
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0answers
7 views

Stochastic Gradient Descent: using minibatch AND small dataset size

My dataset has textual samples where the number of the samples is <1000. I'm training an NERecogniser by using spaCy library. Is using minibatch important in my case (small dataset size)? I ...
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0answers
158 views

Calculating a sample size based on the target width of a confidence interval with stratification

I am reviewing a sampling design devised by a colleague and completely fail to understand it, although I am not a novice in statistics (but not a huge expert either). The said colleague is no longer ...
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0answers
17 views

Please help me to find the sample size?

I conducte a survey in a state related to perception regarding child sex ratio, for this I selecte the two district with high and low child sex ratio,now I travel with that how I selecte the sample ...
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0answers
18 views

Sample size in logistic regression [duplicate]

When talking about minimum sample size for logistic regression, do they mean the total number of observations in the study, or do they mean number of observations in the categories you are ...
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0answers
13 views

Can the range of possible values including the margin of error exceed 100%? [duplicate]

1) I'm working on a sample gotten from users on a website. However, on certain days, the sample size can be as small as 5. As a result, I used the T distribution for my calculations instead of the Z ...
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0answers
19 views

How to calculate a sample size for a longitudinal study with repeated data?

Did you know a program or logiciel that allows to calculate the sample size for a longitudinal study with repeated data ? And if my subjects are nested in some schools, how I calculate the sample ...
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1answer
26 views

How to determine which independent variables to add in a multivariable regression model when sample size is small

As a post-doc I am working on some data that I did not collect myself. The central question I'm trying to answer: is there a difference in the fat mass of neonates born to mothers with gestational ...
1
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1answer
32 views

Minimum number of data to check normality

I want to know the minimum number of data required to check normality of my data, I found in Minitab it should >= 20 , other say should be 30 data, on what basis this number is based, and in this case ...
3
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2answers
47 views

10% rule for sample sizes

In an introductory stats book by Nicole Radziwell "Statistics the easy way with R" , an assumption used for nearly every statistical test (e.g.t-tets, anova, etc) is that the sample size should not ...
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0answers
9 views

Sample size for multinomial response?

Thank you in advance for reading this question! I was wondering, how would I go about calculating an appropriate sample size, given that the output / response is multinomial? I really like the ...
2
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1answer
52 views

Sample size for rare diseases

Disease X has an prevalence of approximately 1% of a very large population. I need to calculate the sample size for a 2-arm RCT for the patients with X. power: 80%, significance level=0.05, expected ...
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1answer
43 views

Power analysis for binomial regression (success/failure)

I've collect 161 people for a study which the original power analysis was based on correlations, but now I've realised binomial regression would be better. I can find a lot of articles on comparing ...
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1answer
39 views

Required sample size to reach adequate power of a test

We got two types of treatment (type 1 and type 2). In our opinion, type 2 treatment has a higher performance and we would like to show this with research. We assume that type 1 treatment has a maximum ...
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0answers
17 views

Minimum Sample Size with the Panel Data; Firms and Obeservations

I'm working on the panel analysis with the data of 20 firms in two nations (10 for each nation). It is an annual data which covers the time period from 1980 to 2015. As it is my first time to deal ...
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1answer
44 views

Is reporting the sample size useful?

I was browsing Reddit (r/science) and noticed that most submissions put the sample size in the headline, e.g. N=100. The same goes for many news sites. Is this information actually useful on its own? ...
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1answer
13 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
114 views

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

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
17 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
10 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
29 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
41 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 ...
2
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1answer
17 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
20 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
30 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
17 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
28 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
45 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' ...