# Tagged Questions

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### How am I using KS test incorrectly in R?

Here are the codes I input into R: ...
103 views

### Mean value of truncated normal distribution

I have a bunch of data where each observation represents an error $\in [0,1]$ (computed error between a variable and it's ground truth). Extra info: These are the results of the difference between a ...
13 views

### About Hypothesis Test In Spatial Regression

I'm doing estimation of spatial lag/error model using R package "spreg"/"spdep". But I can't find any method to do hypothesis test after regression. For example, I want to test whether two ...
56 views

### Two sample $t$ test in R: where did it go wrong?

I am doing two sampled t test on two species of fish. t.test(fish1,fish2) It runs for a year so there are 365 values for each fish, i.e. $(1,0,1,0,0,2...)$ and ...
42 views

### How to test if some data points is drawn from a distribution with linear PDF?

I have some data in the range [0, 1], and from the histogram below, it seems that they might be drawn from a distribution with linear probability density function (what's the name of that kinds of ...
59 views

### Test identicality of discrete distribution

Is there a standard way to test whether two vectors were drawn with the same discrete distribution in R? Something like a Kolmogorov-Smirnov test, but for discrete distributions. I think two-sample ...
113 views

### Can we skip the lower order terms in interactions? [duplicate]

This question is about three-way interaction and the possibility of applying without second lower terms with keeping the main variables in the equation not like the other questions. In fact the other ...
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### Is two years enough for panel data analysis?

I have around 800 companies for only two years period. However, around 200 of them have only one year observation. Is it still possible to conduct panel data analysis with such data Thank you
106 views

### How to statistically compare groups for multiple density plots?

Is there a statistical method to compare these density plots other than ANOVA (MANOVA)? I would like to compare the densities among year within each plot and report which of those distributions are ...
274 views

### How exactly does null hypothesis testing work

I'm trying to gain a better understanding of how null hypothesis testing works. I have 3 questions related to the code below: Am I right in saying the probability of each t value in ...
157 views

### Two-Sample t-Test for Equal Means with unequal variances for large samples

How can I perform a two sample test of means with unequal variances for a very large sample in R? In case of large samples the statistic will asymptotically follow a normal distribution. Which R ...
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### What does “(scores mapped into 1:m using rounded scores)” from the 1-sample permutation test mean?

I'm trying to do an exact paired permutation test. What does this "mapping" mean? ...
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### Durbin Watson test statistic

I applied the DW test to my regression model in R and I got a DW test statistic of 1.78 and a p-value of 2.2e-16 = 0. Does this mean there is no autocorrelation between the residuals because the ...
157 views

### R - power.prop.test, prop.test, and unequal sample sizes in A/B tests

Say I want to know what sample size I need for an experiment in which I'm seeking to determine whether or not the difference in two proportions of success is statistically significant. Here is my ...
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### Identify points significantly outside a regression model

I would like to update my previous question "Methods to determine reliability of measurements using median and median absolute deviation". I have data from biological experiments, that look like ...
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### Methods to determine reliability of measurements using median and median absolute deviation

I have several datasets containing hundreds of variables, measured at the same time point and with the same method. Some of these variables have been measured more often and assume consistent values. ...
269 views

### Is the beta distribution really better than the normal distribution for testing the difference of two proportions?

I'm working at an online agency, where we run a lot of AB testing in order to test differences in proportion between two groups (test vs. control). Standard practice in the industry for testing ...
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### How to test if two populations have the same demographics?

I have 2 population samples for which I want to assess whether they have comparable demographics. What is the right way to test this, that includes multivariate combinations ? I.e I would like to ...
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### How to compute V statistic and statistical test in wilcox.test

x <- c( 9, 5, 9, 10, 13, 8, 8, 13, 18, 30) y <- c(10, 6, 9, 8, 11, 4, 1, 3, 3, 10) wilcox.test(y, x, paired=TRUE, exact=FALSE, correct=FALSE) How do you ...
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### How to handle unequal sample size with multiple factors?

The following dataset shows observations (count data) of cedar trees growing in small, medium, or large forest gaps (i.e. openings). You can see that that there is an unequal sample size and ...
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### Significance of the overall model GLMM using lme4

Maybe it's a basic question, but I'm learning about GLMM using the lme4 package. I'm confused about the way that I can know the significance the overall model using glmer. First, the random model is: ...
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### What is the test used in R in sm.regression to compare reference model with kernel regression?

I am doing bivariate kernel regression using the sm.regression function: http://cran.r-project.org/web/packages/sm/sm.pdf There is an option to compare the nonparametric estimate with linear model. ...
134 views

### How to test the influence of external factors on time series

I need an advice/ best method on how to rigorously test the influence of categorical predictors (states), or their duration (duration of war/peace in this case) on time series. How to prove that the ...
61 views

### Comparing two distributions

I have more than five hundred thousands samples of a continuous variable measured in two groups: a treatment and a control one. I would like to decide whether the measurements follow the same ...
108 views

### What does p-value mean in R?

I want to apply a t-test on two independent samples, and decide whether sample_2 is greater than sample_1. Below are the results for two different t.tests I ran on ...
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### How to compare two sides of patients with multiple measures per patient?

Let's say we have $n$ patients and we did $l_i$ measures of some parameter at the left side of the patients and $k_i$ measures of the same parameter at the right side of them. So we got a table like ...
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### What do these residual patterns tell me?

I am doing a regression analysis with multiple variables and comparing it to a one-variable null hypothesis. The goal is to see which model provides a better explanation. The topic is information ...
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### Wilcoxon rank sum test methodology

I'm comparing the performance of two algorihtms $A$ and $B$ based on a metric. For each algorithm, I have $31$ independent samples that represent its performance. This samples are grouped in two ...
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### SEM for Non-Normal Ordinal Data

In short, I conducted a satisfaction survey in which surveyees are required to answer on a satisfaction scale from 1 to 7: 285 observations, 37 satisfaction variables. Here is an example of what the ...
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### R: Shapiro-Wilk test with relation of W and P-Value? [duplicate]

I'm currently learning about the Shapiro-Wilk test for normality and using R for conducting simple experiments. One thing which is confusing me is that I found some results would produce a high W ...
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### How Can I Simulate Repeated Significance Testing in R

I work in marketing, frequently running A/B tests on websites to determine which variation is best to serve to site visitors. I would like to be able to run a simulation that highlights the perils of ...
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### one way and two ways anova

anova can be used to test the influence of a factor on an output. One way anova is used if we are considering only one factor and two ways anova can be used if we are considering two factors. ...
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### example where comparison of three mean anova and t-test have different results

suppose to have sample from 3 groups A,B,C. The hypothesis H0: the mean of the 3 groups is the same can be tested using 3 independent t test. ...
149 views

### Hypothesis testing with Neyman–Pearson (finding cutoff quantile of Poisson dist)

I am currently trying to solve a problem that should be very easy, yet I am stumped, and help would be GREATLY appreciated!! The background of the question is this: Q: The number of typing errors in ...
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### Testing a prediction hypothesis

I wish to test the following Hypothesis: H = "sales growth from previous year" predicts "sales growth this year" I have the following data: ...
139 views

### Using R to simulate a sampling distribution under $H_0$

We wonder if the colors (of which there are 6) in “Fun Pack” of M & Ms are distributed at random. Let us define as our test statistic $T$ (and there are many ways we could choose to do this) as ...
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### Detecting poaching by age class proportion - suggested test for detecting decrease in given age class?

My dataset consists of observations of individuals, recording the date and the individual's age class. Age classes vary in bin size: 0-4 5-9 10-19 20-40 Example ...
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### Comparing two distributions using Generalized method of moment estimation

If I consider a data X, I want to fit a distribution Y which has a density f(x) but It's not possible to express the moments of Y as function of the parameters. My problem is : 1- to estimate the ...
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### Suspicious Friedman test results

My data involves testing 216 experimental units (computational models) for which one factor (the value of a specific shared parameter of the models) is administered in 4 treatments (i.e. the parameter ...
200 views

### Hypothesis testing - Wilcoxon test, bootstrapping, or something else?

A colleague has developed a treatment for to "prevent falls" in cognitively impaired, psychiatric patients. Since this would be very useful treatment in this population, we especially do not want to ...
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### Which test should be used to compare two mean differences?

Say that I have two groups who received two treatments, and now I want to know if they progressed AND which group progressed more. I first did a paired t-test to know their progress, respectively, and ...
990 views

### How do I test if two (non-normal) distributions differ?

I have read about Student's t-test but it appears to work when we can assume that the original distributions are normally distributed. In my case, they are definitely not. Also, if I have 13 ...
242 views

### R: power calculation for beta coefficient

I am interested in calculating the power for the beta effect size, for example ...
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### Why isn't this code for prop.test giving me the right answer for test statistics?

I have used the following line of code but it doesn't give me the right answer for (chi-squared) test statistic while it gives ...