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].
0
votes
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).
...
2
votes
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 ...
0
votes
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 ...
0
votes
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 (...
1
vote
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 ...
0
votes
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 ...
0
votes
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 ...
0
votes
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 ...
2
votes
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 ...
0
votes
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
votes
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 ...
2
votes
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 ...
1
vote
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 ...
0
votes
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' ...
0
votes
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.
0
votes
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 ...
-1
votes
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 ...
1
vote
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. ...
0
votes
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 ...
0
votes
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
votes
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, ...
0
votes
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 ...
0
votes
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 ...
0
votes
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 ...
0
votes
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 ...
4
votes
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 ...
1
vote
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 ...
1
vote
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 ...
1
vote
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 ...
0
votes
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 ...
0
votes
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}...
0
votes
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. ...
2
votes
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\}...
1
vote
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 ...
0
votes
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/...
1
vote
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 ...
0
votes
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 ...
0
votes
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 ...
1
vote
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 ...
0
votes
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 ...
1
vote
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 ...
4
votes
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 ...
0
votes
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 ...
3
votes
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 ...
0
votes
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).........
0
votes
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 ...
7
votes
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 ...
0
votes
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 ...
0
votes
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 ...
0
votes
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 ...
