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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Could Use Assistance On A Work Project [on hold]

This might be a little unorthodox, but I could use some assistance on a work project. I work for a small company. We don't have any formal data sciences or analytics department. I was tasked with a ...
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2answers
41 views

How to interpret the means of different sample sizes

I have three sets of data I am working with. The N of each are all vastly different and the means are also very different. I obviously don't want to interpret it so black and white because I know the ...
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2answers
31 views

How could calculate sampling size for 95% confidence in a unique distribution?

I made a big list of words that I claimed more than x% of them have dictation error. For showing my confidence of claim I need to show a sample(random) that prove it(because I can survey a sample list ...
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30 views

Sample size for clinical research

I determined the sample size already (25), but I want to know if it has to be increased because of a minor change. Our study consists of two groups - one will be sedated and the other will not. For ...
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5 views

Sample size calculations (based on proportions) with a 3x2 factorial design

I'm trying to calculate the sample sizes for a three arm RCT (1:1:1). After allocation to each arm, patients will get further randomised (1:1) for a second intervention. See the below Table. I've ...
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37 views

Very Basic Question on Sampling [closed]

For determining sample size , why is to focus on the unbiasedness and accuracy of the estimates ? In a simulation study , authors chose that sample size for which they get unbiased and accurate ...
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28 views

How to calculate the sample size for proportions using Effect Size?

I need to determine the sample size for my experiment. In my experiment I will select a set of x projects, from a population of N project. For the sample x projects will apply a treatment to know the ...
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11 views

How important is normality assumption for a two-way repeated measures ANOVA?

I want to use two-way repeatead measures ANOVA. The dependent variable is CRP levels in three different time points in five different group of patients. Each group includes 40-42 patients, so that ...
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1answer
17 views

Sample size for mediation analysis

My study is on the relationship of college persistence of students, perception of students on student affairs services and their academic integration. I was suggested of using mediation analysis. May ...
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1answer
20 views

Sample Size Determination for Multinomial Proportions

I have a number of samples of different sizes from a population of unknown size. The data are market shares for five different products within a category (so they sum to 1). I want to know how many ...
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18 views

Use of One Way ANOVA

In order to analyze the financial performance of Life Insurance Companies in India during a period of ten years, year wise certain financial ratios have been computed for all the selected companies. ...
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30 views

How to calculate the required sample size for x% accuracy?

I've made an algorithm for parsing some strings, and the question I have is how many random strings should I collect and test to get an estimate of how good the algorithm is? Testing on all is not ...
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26 views

How to calculate sample size for a disease-specific survey?

I want to find out the quality of life among diabetes patients, on what basis do I calculate the sample size? Can I use diabetes prevalence as my population proportion?
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14 views

How to determine sampling size for large populations in Stratified Sampling?

I am designing a survey with more than 50000 population in each stratum and which consists of these interests (I am still not sure of how many strata are there): The respondents will be composed of ...
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15 views

Sample size for Dunnett's multiple comparison

I want to calculate the sample size (or power analysis) for a design with two treatment groups and one control (placebo). I will use the Dunnett test for multiple comparisons. Intuitively, if I ...
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0answers
9 views

How many samples do I need for OCR problems?

I am thinking about collecting samples of hand written digits (0 to 9) from people. I'll try to test different algorithms for optimal character recognition- some form of neural network and random ...
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17 views

Avoiding over/under fitting & validation set size

I'm using a PLS model associated to FT-NIR spectroscopy to predict some properties of biodiesel. At the moment, I'm trying to optimize the number of factors I should use to do the calculations. ...
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16 views

Taking longer sample should not reduce the variance of the mean

I have not realized completely why n times longer samples should give you n times shorter variance. However, I measure performance of my programs and there are some fluctuation due to PC state ...
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1answer
49 views

Increasing sample size of multivariate data with bootstrapping

I'm trying to perform variable selection methods on a small data set (approximately 100 observations with 14 predictors each). Is there any way to increase the sample size with bootstrapping? Are ...
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13 views

unequal sample size

I am completing a Likert-scale based questionnaire (strongly agree--strongly disagree) for a perception study. My primary issue is that I hope to compare two groups (one major (A) vs another major ...
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1answer
31 views

Is this training dataset enough for training and testing classification model?

My training dataset contains just 2 classes with 40 features. In case 1, class 1 has 35 samples and class 2 has 700 samples. In case 2, class 1 has 65 samples and class 2 has the same value as ...
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17 views

sample size of infinite population and alternative comparisson

I need to compare two alternative methods of manufacturing a product, say A and B. I wanted first to dermine the sample size of ...
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0answers
9 views

SPSS Comparing means between groups

I am currently working on a project about the performance of Himalayan mountaineering teams. I want to compare differences between these teams on the basis of the mountain they attempt to conquer and ...
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36 views

Appropriate Sample Size Formula

I have a uniform distribution set which contains different similarity scores. This similarity scores is linked with documents in which I am planning to examine. However, this set is big, and it is ...
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39 views

How to analyze survey data, interval or ordinal, and how to account for nonresponse bias?

I have a question regarding a survey. I gave a test to people and they were asked to rate the tester on a scale of 1 to 5, 5 being they liked it and gave it the highest rating, with 1 being the ...
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1answer
27 views

Clarification on the rule of 10 for logistic regression

Been brushing up on my logistic regression and I've seen a couple of things about the one in ten rule. To illustrate my current understanding (or lack thereof) lets consider a case with only two ...
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21 views

Is it correct to use a test dataset that is much bigger than the training dataset?

I am addressing a machine learning problem where I am simulating a reduction in the training dataset keeping a constant hold-outs sample for testing purposes. Usually a good ratio between training and ...
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36 views

Sample size when using GPS-trackers to analyze movement of reindeers

If one were to try and analyze the movement of ~2 500 reindeers before and after a (man-made) change in landscape have occured. Specifically how spread out the herd is, both as a whole and if there ...
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27 views

To work out 7 point Likert scale sample size, can I increase the MoE to 7%?

I have a survey that consists of 7 point Likert scale data. Each sample is quite expensive to collect, so I'm trying to keep the sample size as small as possible without compromising the results. My ...
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28 views

Friedman? Unequal samples sizes

my students were involved in three different simulations. I was asked them to rate their satisfaction with these simulations on a 5-point Likert scale (several items). Unfortunately, I have 60 ...
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1answer
21 views

Comparing retention rates with differing sample sizes

I'm looking to compare the retention rate of people who attended an event and those who did not. The list of those who did not (70) is significantly larger than those who have (28). Here is an ...
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534 views

Making up for a low sample size by increasing the number of observations

What exactly is the error that is made in the following judgement? "I cannot increase my sample size, so I'll make up for the low number of subjects by asking the subjects to perform more trials, ...
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23 views

How do “stacked” repeated samples influence our rules of thumb for minimum samples size in regression?

A professor in one of my graduate statistics courses once said, when briefly reviewing simple linear regression: "I would never EVER fit a line to fewer than 8-10 data points, it would make me ...
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2answers
37 views

How to empirically show that a certain quantity approximately follows a normal distribution?

To motivate some theoretical work, I need to show that two certain variables (say $X$ and $Y$) approximately follow a normal distribution in actual datasets. I have one large dataset with about $300$ ...
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29 views

Logistic Regression as Data Transform?

I'm analyzing medical research data with a small sample size that is not easy to replicate because the data were collected on an invasive procedure. The outcome variable is binary. There are two ...
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25 views

Experimental design for high dimensional model

I am running a computer model with a lot of inputs ( > thousands). I am not familiar with this area, so may I ask for any instructions/directions on how to make design on such high dimensional space? ...
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40 views

How to interpret LASSO graphs

I was given access to a total of 19 pieces of deceptive and persuasive texts along with a percentage on whether the readers of the said text followed through with the text's demands. The 19 cases ...
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1answer
25 views

Reference for Two-level Logistic Regression

I am an undergraduate student . In this level , we aren't taught Multilevel Logistic Regression. But my project topic is Multilevel Logistic Regression and I am ...
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1answer
19 views

Sample Size Calculation for intervention designed to decrease time to event outcome

I've been asked to provide a sample size estimate for a RCT of an intervention designed to reduce a waiting time. The investigator believes a reduction of 30 minutes would be important. As expected, ...
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1answer
57 views

About the central limit theorem and statistical testing

Wikipedia states that In probability theory, the central limit theorem (CLT) states that, given certain conditions, the arithmetic mean of a sufficiently large number of iterates of independent ...
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10 views

sample size query

I have a question regarding the sample size required for a project i'm involved in. Without going into too much unnecessary detail, we have processed 905 cases (in the last day) and 4 of them were ...
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1answer
31 views

Testing the difference between two samples with very different sizes using an un-paired t-test

I want to test wether population A is significantly different from population B (at 5% confidence interval). I need to do it for each variable using an un-paired t-test, since my data are normally ...
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1answer
26 views

Given a correlation matrix and sample size, how to calculate which correlation coefficients are statistically significant?

Suppose you are given a correlation matrix and a sample size. How do you calculate which correlation coefficients are statistically significant? If there are $K$ variables then there are $K^{2}$ ...
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1answer
96 views

Defining a Population

I am tracking monthly data entry errors in a customer service dept. of 20 people, and then doing regression and correlation analysis on variables like typing speed and data entry error. I have data ...
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11 views

Statistical significance in a small peer group

I am looking at the gross profit margins in a industry where there are 10 companies. The company I am interested in has a gross profit margin of 28% and the mean gross margin across all 10 companies ...
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1answer
55 views

Durbin-Watson Critical Values for Large Sample Sizes

My sample includes 3,627 observations but I can only find tables displaying critical values for the Durbin-Watson test for sample sizes 2,000 and below. Where can I find tables for sample sizes ...
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20 views

Minimum sample size for Factor Analysis? [duplicate]

What is minimum sample size required for using Factor Analysis? I have a data-set with 22 cases and 12 features. Is this sufficient? (I can't increase number of cases in my research, it is restricted ...
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1answer
36 views

Sample size calculation, linear regression

I have just had my viva and my sample size calculation was criticised as it was based on r2. I was told to base the sample size on the minimal magnitude of association. My outcome variable is HbA1c, a ...
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7 views

Sample Sizes Based on Cost Efficiency

I am planning a biology experiment that is testing the predictors of biological markers.These predictors are: Gender.(Binary) Smoking status.(Binary) Alcohol consumption.(Binary) Hiv infection ...
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39 views

Sample Size for Comparing two Measuring Tools

Let's say I have two devices that measure the same thing: the thickness of an object. Knowing that device 2 is more accurate and precise, I wish to see how accurate device 1 (how close do the readings ...