Refers to any statistical complication or problem due to having few data.
2
votes
0answers
51 views
Structural equation model with very small samples
I have two sets of a longitudinal data that I hypothesize to measure same latent construct.I am trying to test this hypothesis using Structural equation modelling technique. Basically, I am trying to ...
1
vote
0answers
31 views
Small sample, many variables
I am working on some applied research. I have a small non-random sample (n=90), and many variables >50 IVs (mix of nominal, ordinal, interval) and 6DVs. The data collection instrument itself was ...
1
vote
1answer
45 views
What to do against sampling/selection bias?
Let's say in machine learning the test cases are biased towards one or more options.
For example when there are 100 (just an example) test cases in total and every test case has a color to be ...
1
vote
4answers
127 views
Measuring representativeness of a sample using covariates
I was provided with quite a small sample of labeled (variable of interest) observations to train a model to predict unlabeled observations. All the observations are associated with many covariates. ...
1
vote
0answers
12 views
How to handle samples with many replicates for population estimation,when sample size is small?
I have a sample with very small sample size ($n<10$) and I would like to estimate the population mean. However, some of the samples are replicates (for instance, sampled at the same location).
...
0
votes
0answers
28 views
How do I bin when fitting to power law?
I want to visualize the readership statistics on my blog posts, and see how well they fit to a power-law distribution. However, testing for power-law is notoriously difficult, so I wanted to ask for ...
0
votes
0answers
20 views
Dependent and unbalanced sample size
I have a dosimetric data from a radiotherapy planning for (n=21) patients. For each patient, a treatment plan was simulated in treatment planning system by changing the x,y,z parameters of the ...
0
votes
1answer
55 views
Determining butterfly weight distribution
I'm a researcher studying a specific butterfly species. I've conducted an experiment where I measure the weight of this species at different locations on the earth. The data is cateogorical and ...
0
votes
0answers
21 views
confidence interval with small supopulations
I am currently using a large dataset (n=1.850) composed of smaller samples of several countries. I am currently aiming to describe the sample and infer to the population using simple frequencies ...
1
vote
1answer
73 views
Compute the variance of parameter estimates given limited number of samples
I'd like to infer the variance of estimated parameter $\hat\theta$ of the density function of $f(x;\theta)$ given only a limited number of samples $X_1,\cdots,X_n$.
Bootstrapping doesn't perform well ...
1
vote
1answer
83 views
(When) Does simulating a larger sample from a small sample yield better results?
I am trying to classify a set of $p$ predictors into 5 classes. But my sample size $n$ is rather small, so I fear I won't get a very robust estimate.
Now an idea would be to subset my data for each ...
0
votes
0answers
33 views
Mean group score vs each individual participant's score?
I am conducting a questionnaire-based study with N=99. The participants are school-age language students who were tested in 9 small groups of size 10-12 drawn from existing school classes. The meat ...
4
votes
1answer
239 views
Disagreement between normality tests and histogram graphs
My data consist of compaction measurements from 3 different cell types (X,Y, and Z). My goal is to know whether there are "significant" differences between these measurements, so I have tested for:
...
3
votes
0answers
47 views
Limits to tree-based ensemble methods in small n, large p problems?
Long time grazer, first time poster. I'm hoping to gather people's opinion on the following:
Tree-based ensemble methods such as Random Forest, and subsequent derivatives (e.g., conditional forest), ...
0
votes
0answers
61 views
What are the limitations of graphical displays with a small sample size (n=18)
I have a small sample size (n=18) and am performing univariate analysis. I have graphical displays (stem and leaf plot, dotplots, boxplots and a cumulative distribution plot). I am trying to ...
3
votes
0answers
116 views
Non-parametric confidence interval for a small sample
I have a question about measuring a confidence interval for a binomial success rate using from a "small" universe. I should say that I don't think that the underlying distribution is binomial for ...
0
votes
1answer
115 views
How to use OLS or NLS on very small sample size?
right now I am facing the problem of handling a very small sample size which consists of 8 observations with 24 variables.
I would like to do first just simple OLS with one dependent and 23 ...
7
votes
1answer
436 views
Is significance of the p-value reliable with extremely small sample sizes?
As I'm completely new to statistics and clinical trials, I would ask you for help and clarification.
Let's assume we have 2 really small samples (each of n = 2, or so) derived from two normally ...
4
votes
3answers
176 views
What are good techniques for modeling small datasets?
I’m working on a classification problem. However, my training dataset is very small (just 800 items in training dataset) and each data item contains a small number of features (just 5 features). ...
1
vote
1answer
149 views
Is PCA appropriate where n<p?
This question is an extension of one I asked a few weeks back, here is the link:
PCA and small number of observations
I will restate that I am interested in the use of PCA in situations where n ...
0
votes
1answer
136 views
Dealing with a small sample size
Suppose we have a data set consists of, say, 5 or 10 observations. The only thing we know about this set is that it came from a positive right skewed distribution. Now suppose we want to fit a ...
0
votes
0answers
93 views
Non-central chi-square for small sample likelihood ratio tests?
I am interested in small sample performance of likelihood ratio tests.
I have found empirically that the null hypothesis distribution (obtained by permutation) in small sample situations can be fit ...
1
vote
2answers
98 views
Comparing patient and control group results of a survey
I have data from a survey given to a patient group and control group. Both groups completed the same exact survey (Likert scale). One group has an n of only 5 or 6, the other n was about 15.
What ...
1
vote
0answers
34 views
Considerations for choosing transformation on small samples?
For a biological investigation, I am taking measurements of a set group of individuals over five points in time. The measurement is always between 0 and 1. Unfortunately, I was unable to measure every ...
1
vote
0answers
47 views
Sample size RM-ANOVA
I am comparing Shannon entropy values (for zone occupation) obtained by soccer players during small-sided games in three pitch dimensions. I am also scrutinizing differences between expertise level ...
1
vote
1answer
198 views
How to test for differences between two group means when the data is not normally distributed and the sample size is small?
I have a preliminary study with very small sample size (n=26), and I want to test for differences between males and females and similar things, so I have to divide the sample and make comparisons of ...
3
votes
1answer
407 views
Using Student or Wilcoxon test on small sample without information on the normality of distribution
I have three subjects in a qualitative study. I am comparing the features of their writing before and after treatment.
I have no idea about the normality of the distribution since they were selected ...
2
votes
1answer
92 views
How to estimate the probability that the mean of an unknown distribution is over a threshold given small sample size
I am trying to quantify my concerns regarding a proposed incinerator in our community. The company is basing its potential to emit dioxins (a class of chlorinated organic compounds with a reference ...
0
votes
1answer
323 views
What are the problems with small sample size based predictions when using time-series data?
I had to put the majority of the question in the textbox as Cross Validated didn't like the fact my question was too long....but here it is, in terms of what I wanted to ask:
Due to a small sample ...
1
vote
2answers
373 views
What significance level is required with a small data set?
My apologies if this has been answered here. It's my first time here.
I am a developer by trade. I am not really into this thing, but I was asked to do some data simulation using SPSS. But I am not ...
0
votes
3answers
1k views
What statistical test should be used when sample size is small (n = 13)
I have collected data from employees at 13 branches of a bank and also administered customer satisfaction scale to customers of each of the branches. As a result, I am unable to have pairs of ...
0
votes
0answers
290 views
Explanation for confidence interval for quantile with small data set
From one of the answers in this post, Confidence interval for median, I have found a way to get a confidence interval for a quantile, and my understanding is that this is an appropriate method for ...
7
votes
3answers
404 views
Dimension reduction techniques for very small sample sizes
I have 21 socio-economic and attitudinal macro-level variables (such as percentage of mothers aged 24-54 not employed, percentage of children aged 3-5 in nursery schools and so on). I also have data ...
2
votes
1answer
278 views
Parameters’ uncertainty for small sample size
Suppose we have a small set of numbers (5 to 10 observations), and we’re trying to fit a distribution to this set. Also, we know that all numbers are positive. I tried to fit lognormal, but I’m not ...
2
votes
2answers
85 views
How to estimate loyalty to service?
Let's say there are two services $A$ and $B$ that solve same problem. We would like to know which one users more loyal to. Loyalty $L(X)$ is probability that user will use service $X$ when asked to ...
2
votes
0answers
103 views
How should I account for small samples in a larger data set? Should I remove them?
We're trying to develop a simple tool that will help our teams optimise their clients' Facebook posting strategies. In our experience, time of post can have a big impact on audience response; but ...
2
votes
1answer
182 views
Real data collection with small population
I performed an actual scientific experiment and I was only able to collect 2 data points. I am wondering what kind of statistical method I can use to analyze the data.
I performed a similar ...
1
vote
1answer
191 views
Using averages of two different size groups
I'm not really "into" statistics, so I could use a hand on this one. I have two small groups, one has 12 students and the another one has 6.
Both groups answered a questionnaire and I'm trying to ...
1
vote
1answer
146 views
Statistical tests for low sample numbers in both indendent groups (n=3 and n=1)
I've been asked to analyze some data for an experiment that's already been done. 15 rats were raised in 5 groups of 3
No treatment
Saline treatment (control drug is delivered via saline)
Drug ...
0
votes
0answers
145 views
Normality test for small samples
I get a little bit confused by the conclusions I can take or not with these small samples.
I have been measuring the degradation of a pollutant for 9 days. I measured the remaining concentration and ...
2
votes
0answers
256 views
Halton sequence vs Sobol' sequence?
From an answer in a previous question, I was directed toward the Halton sequence, for creating a set of vectors that covered a uniform sample space fairly evenly. But the wikipedia page mentions that ...
1
vote
0answers
206 views
Mixed effects models issue and correlation question. Getting desperate
I have been trying to get answers for a while, and have looked up every help section and tried other stats sites. I have a thesis that I need to be completing shortly, but one set of data has been ...
1
vote
0answers
433 views
What is the minimum sample size for panel data analysis?
I am working with a panel data and want to perform a regression analysis (OLS, fixed effects model or random effects model). The panel data is unbalanced with N varying from 7 to 13, and T=11. I am ...
1
vote
3answers
3k views
Non-parametric test for unequal samples with subsequent post-hoc analysis?
Is it okay to perform a Kruskal-Wallis on four unequal samples? Further to this, is there a subsequent pair-wise post-hoc suitable for two unequal sample sizes?
4
votes
4answers
12k views
Minimum sample size for unpaired t-test
Is there a "rule" to determine the minimum sample size required for a t-test to be valid?
For example, a comparison needs to be performed between the means of 2 populations.
There are 7 data points ...
1
vote
4answers
382 views
Is it ever appropriate to fit a regression on 3 points?
Lets assume we only have 2 variables, x and y, and our model (in R code) is lm(y~x). Given ...
4
votes
1answer
125 views
More details on bootstrap procedure to estimate confidence interval of sample SD
I originally asked the question in this post, where I explained that I only have 25 measures at my disposal. Hence, computing the sample SD $\sigma_x$ and assume it's the one from the distribution ...
3
votes
2answers
314 views
Theory on discriminant analysis in small sample size conditions
I see a similarity between a problem I'm working on and Linear (or Quadratic) Discriminant Analysis when the sample size is smaller than $p+1$.
I'm interested in theory bounding the generalization ...
1
vote
3answers
488 views
How many cases are needed for an extrapolation?
In social science it is comon to use sample weight to post adjust the sample so that it fits to a given basci population. There are algorithms to calculate how many cases you need to have a ...
0
votes
1answer
111 views
Counterintuitive result for random sample
Say that you're making a political research, and you want to know how many people vote to Party A and how many vote to Party B. (There are only two choices.)
You make a random survey of 10 people, ...
