# Tagged Questions

Refers to any statistical complication or problem due to having few data.

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### When using a limited data set, how can I use excel to forecast future values?

To preface, I am a statistics novice, but I am faced with a problem that I cannot seem to be able to satisfactorily resolve. The problem is as follows: I am working to forecast future sales for one ...
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### Multiple regression analysis with 22 data points and 7 independent variables [on hold]

I am working on my thesis and want to do do a regression analysis to find the effect per 'problematic factor' (see attachment) on 'Duration' (see attachment) or 'Costs' (see attachment). Chance here ...
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### How to obtain statistical information from a Likert scale with a sample size smaller than the number of questions?

Research and sample properties I'm measuring the degree of a certain concept related to marketing and sustainable development throughout an entire industry. The theoretical model is depicted next: ...
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### Variance-covariance matrix after cluster-robust SEs with clusterSEs package in R

Is it possible to extract the variance-covariance matrix after bootstrapping the standard errors (clusterSEs package)? I want to use cluster-robust standard errors since the number of clusters in my ...
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### small number of treated and control units, with time series

I'd like to examine treatment effects in a before-after randomized experiment where the number of treatment and control units is small, but where I do have a long time series of data for each unit. ...
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### Comparing time series of small N group of individuals but reasonably lengthy time series

I have been given some data about pre and post release behavior of a small group of rehabilitated animals in Africa, with some measures of success being how much food the animals eat in the wild and ...
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### Is autocorrelation not worth addressing with small N?

Consider a simple regression context in which there is a small set of response values, $Y$, and corresponding dates, $X$. (For simplicity, we can assume the dates are equally spaced.) We would like ...
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### Minimum sample size to check second order stationarity

I can understand second order stationarity refers to weakly stationary processes in which mean, variance, and autocovariance do not depend on time. But is it possible to check weak stationarity/second ...
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### Grouped monthly sample sizes

This will be really simple, but I'm having a hard time figuring out how to Google this. Let's say we have 12 months of trailing data on something like "Calls per month," and that data is on the low ...
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### How to choose the test set size when the training set size is given?

I have data on 64 subjects collected in a medical setting. With the help of ROC curve analysis and bootstrapping, I have identificed two predictors for illness(present or not present) in the group. ...
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### How to treat subsamples that differ in respect to the dependent variable prior to any treatment?

I have conducted an experiment on a sample that consisted of both male and female students to see if a specific emotion influences moral judgment. My research goal didn't involve any hypothesis about ...
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### Factor Analysis with low sample size

Does anyone know of references to support conducting EFA with a low sample size?
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### Alternative to Wilcoxon signed-rank test with sample size < 6

I have to make a statistical analysis of only four (n=4) data pairs. I have tested two specific warm-ups for 4000m Team Pursuit in track cycling, and used a 250 m. sprint test as a meassurement of the ...
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### Comparing large and small populations

Here is a hypothetical that mimics my actual data (sensitive so cannot post actual details). I have 149 students in a class. In preparation for the final exam (which is pass/fail, NOT ranked), I held ...
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### Proportion Sample Size Estimation? Cluster Sampling

I was asked by someone running a food drive to help with the following problem: Food is being collected in bins, which hold about 1,500 lbs of food each. They are looking to collect about 500-600 ...
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### Statistical analysis for replication in very small experimental datasets

A colleague does replication on a quite coslty experiments. There are four different conditions, each one duplicated. The outcome with $4\times 2 = 8$ points is illustrated below: The analysis is ...
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### Statistical analysis options on small datasets

first of all please excuse my poor knowledge of statistics I'm currently teaching myself and have no training in it. To test correlation I have created a data set that indicates by how much 5 cities ...
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### Bootstrap for small sample

Does bootstrap method help for small sample? In my mind, bootstrap is a solution when you don't have belief in a normality assumption. If your data is random enough, it might be convincing to sample ...
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### Sampling size question [closed]

I wanted to know the sampling size of a population where size is low and moreover it doesn't follow a normal curve. Moreover I wanted to roll out quality numbers at monthly level as the weekly level ...
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### Can I run generalized linear mixed models using lme4 on very small sample sizes?

I am analyzing data (size/survival) of two groups of fish (Group1, Group2) mixed together in tanks with two different environmental variables applied at two levels to the tanks, e.g. +Predator/-...
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### How to ensure sample independence across iterations when using the EM algorithm?

I have a problem which uses the EM algorithm. For my purpose, I would like to run it such that the samples used in the $t$ iteration are independent from those used in the $t+1$ iteration. One way to ...
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### Intrarater reliability test for a single subject?

I have repeatedly measured the volume of the brain of 1 subject in an MRI study. Measurements were acquired by the same rater (myself) on three separate occasions resulting in three measurements of ...
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### Minimum sample size at the last stage of multistage sampling

We're conducting a two-stage survey. First stage is schools, second stage is students. What is the minimum number of students per school that we need to sample? I remember reading that the minimum ...
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### Normality and homogeneity test for small sample size

I would like to inquire if testing for normality and homogeneity is still necessary for my data from an experimental where trials were done only three times. Or can I directly perform ANOVA and post-...
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### Adjusting for variance-sample size dependence

In many survey results that are released to the public with respect to ranking (whether it be school ranking, city crime rates, etc.), one of the many criticisms of these is that some which have small ...
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### Is there any constraint on number of data points in Arima?

Can I build an ARIMA model on only 36 data points?
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### How do I evaluate the impact of sample bias on the generalizability of my findings?

I am performing a regression analysis to identify predictors for my DV, using survey data. When comparing auxiliary information on my participants (in my case firm size and industry) to the available ...
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### Weighting method for small sample size

When I try to apply RIM weighting to correct the selection bias in my survey data, some weights become very small, as the bias is quite substantial. Also, my sample size is relatively small. As a ...
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### non-normal one sample t test N = 19

I have sample data that appears to be right skewed and the Shapiro-Wilk test in R returned: W = 0.83092, p-value = 0.003334. I need to test the confidence that the population mean is different from 0,...
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### Estimating a “true” value with a noisy number of additive noises

I want to recover an estimate of the "true" value of a variable from a small set of noisy observations (5–20). I have an a priori model describing the physical process that generates the ...
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### Help me inform multiple regression coefficients with additional dataset

I have a data set with 24 year on year observations. That is for a single company. I have around 500 companies with incomplete datasets (i.e. with missing values). I am trying to predict a Y ...
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### Multiple hypothesis correction - small n, large p?

I have some biological data (expensive), with only 3 replicates/"samples", measuring methylation level of 450,000+ loci. I am doing hypothesis testing comparing 3 samples of one group to 3 samples of ...
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### Calculate a slope with only 3 points?

I have a dataset that includes repeated counts of individuals at 3 successive time points. I have 8 experimental groups, with 5 replicates each (count repeated over 5 days). My goal is to obtain the ...
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### Minimum number of observations needed for penalized regression?

I'm wondering what should be the minimum sample size to perform ridge, lasso or elastic net regression. I have a binomial outcome that I want to relate with a set of features (18 features in some ...
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### repeated measures analysis for small sample size

I have an intervention study with a very small sample size and am trying to decide the best way to analyze it. Any suggestions would be extremely helpful. Here is some more information: Measurements ...
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### Panel data with small N. Is it ok to use “lme”?

I have longitudinal observations from 6 individuals. For each individual, there are 29 time points when data have been collected. Can I use "lme" in R to estimate a model? Should I check for ...
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### Can I use growth curve modeling with N=6 and 29 time points?

I have data of six children tracked for 29 time points. I am interested in the change of some measurements over time. I would like to know how children differ from each other. Do you think I can use ...
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### Modeling bias in reviews of conference papers

An article in Science Magazine claims that A little bias in peer review scores can translate into big money, simulation finds . The paper referred to there is paywalled, though. Can anyone point me to ...
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### Quasi-experiment: sample size & statistics

I am conducting a quasi-experimental research in a school, where I have access to 100 students who are chosen as classrooms and who will be the participants of the study. I am interested in the ...
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### One-sample test, small sample size (n=3), non-normal data

I have approximately 5,000 variables, each with 3 data points. These numbers are ratios, i.e. bounded at 0 and generally non-normal. I'm interested in testing whether the mean of each of the 5,000 ...
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### What if no Model fits and no non-parametric alternative exists?

I'm doing analysis on data from an ecological field study. I have fields (n=12) of different age. I treat age as a factor (age class) having 4 levels (1,3,5,and 7/8 years old). Hence the number of ...
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### Test for difference between small number of Gaussian-like time series

I'm looking to test for a difference between populations A and B. Each population is made of three time series which can be modeled well with a Gaussian or Gaussian mixture, and each have 55 data ...
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### Small sample sizes for some categories, not for others and ranking them?

[nb: I have zero stats/probability/etc background, but write code; apologies] I'm playing around with some game data - for example, a player has with each ship: 232 wins, 219 losses as "Apocalypse" ...
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### Correction for multiple testing on a modest number of tests (10-20) with FDR?

False Discovery Rate (Benjamini-Hochberg) is typically used on 'Big Data', such as genetic studies using 100s of tests. But can it also be used on smaller numbers of tests? For example, looking at the ...
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### Sample size for large population with rare events?

I want to calculate what fraction of the US population, say 300M, responded to a commercial shown on TV based on a small sampling of data. I think only about 100,000 will respond, 0.0003% How ...
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### Performance of a classifier change heavily

I'm using a data set of 32 face persons and a svm-rbf to classify and a random group of 70% for train and 30% for test. The problem is that my results are heavily dependent of the random group used ...
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### Residential Real Estate Appraisal

Appraisers use adjustments to derive the value of a subject property. For example, if a similar house has 100 more square feet of living space, and sold for \$210,000, we deduct the value of the space ...
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### Graphing small samples

I have a small data set of 14 separate times to complete a task. However I am having difficulty finding an appropriate graph to use to graph the data. If the sample was larger I would use a box plot ...