# Tagged Questions

36 views

### Using R to calculate qt (t-dist) using qf(f dist) help?

I am having quite some trouble using R to calculate, say, qt(0.975,6) using qf instead of qt. I know the relationship between the t-distribution and the f-distribution which I understand as follows: ...
228 views

### Normal approximation for large data set?

I have a dataset that is highly skewed. See image below: When I transform the data I get the following histogram that makes it look normal: This data however is not normal. I get a p-value of ...
39 views

### chisq.test with R

I want to do a Goodness-of-Fit test of my data and the Weibull-distribution. I have estimated the Weibull distribution using the survreg-function in R. Now I want ...
16 views

### Error when using 'mclust' package for mixture model estimation [migrated]

When trying to perform a univariate mixture model estimation, R package mclust produces the following output with an error: ...
12 views

### Limiting the range of possible values for distribution fitting with GAMLSS in R

I'm trying to fit ST5 distribution for reaction times with GAMLSS. Sometimes mu parameter of the distribution is negative, which is implausible. Is it possible to limit the range of parameter values ...
61 views

### Normal Distribution with random mean and standard deviation

When trying to code this in R, I'm getting very confused about what to do. Apologies if my terminology is incorrect but I would be grateful for any advice. The Problem: I have been given two normal ...
107 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 ...
182 views

### Determining probability distribution for datasets with missing values

As a part of my exploratory data analysis (EDA) prior to further analysis, I'm trying to determine a probability distribution of my pilot dataset's variables. A particular feature of this dataset is a ...
26 views

### Have Narrow Distribution - Need Standard Distribution

I am building a model in R using GLM based on this predictor variable. As you can see, the data is concentrated in the center of the distribution, and then falls off sharply. Is there a ...
46 views

### How to test whether a distribution follows a power law?

I have the data of how many users post how many questions. For example, [UserCount, QuestionCount] [2, 100] [9, 10] [3, 80] ... ... it means each of the 2 users posts 100 ...
40 views

### How to separate distributions from weighted dataset?

I’m trying to separate two component distributions of an apparent finite mixture from a weighted dataset (determined by a weighted.histogram). I've a set of data and weights only for a part of the ...
37 views

### 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 ...
99 views

### Tail probabilities of multivariate normal distribution

I would like to compute tail probabilities of the standardized multivariate normal distribution for different dimensions. For example, in the case of bivariate normal I need to compute the gray area ...
110 views

### Issues with fitting distribution to heavy-tailed data

I am currently trying to fit distributions to some heavy tailed data-set (see the data set below) and have a hard time producing good results: ...
71 views

### Probability distribution for right skewed data

My question is very similar to this previous post. I'm searching for the right distribution family to use in a GAM. My data are disease occurrence on benthic organisms (continuous response variable) ...
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### Left skewed distribution implementation generalized linear model

I am very new to modelling and I have a question. I am using a generalized linear model (glm) for my data in R. My response variable is however skewed to the left ...
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### fitdistr loglik in R

I am fitting a few time series using fitdistr in R. To see how different distributions fit the data, I compare the log likelihood from the ...
96 views

### probability distribution for heavy zero, right skewed data

My question is almost identical to this one. Im searching for a probability distribution for skewed data that allows for zeros. The purpose is to fit a GLM model. My data on species-area distributions ...
29 views

### how to fit a zero inflated NB distribution with large mu and sigma by fitdist + gamlss functions

I've been trying to figure out how to use gamlss.famliy Zero inflated functions (e.g. ZIP) on the data. A descriptive stat on my data is as follows; ...
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### How can I generate ensembles using Copula?

I just got buried in a mountain of math and papers, and I am so confused. So basically, I have data (Probabilistic QPE) from which I have extracted 99 quantiles (1%, 2%, ... 100%) to sample the CDF ...
33 views

### Decomposing a Combination of Distributions?

Let's say I'm studying the distribution/log-distribution of a random variable that may actually be the result of a combination of distributions. What are the ways I can check for this and possibly ...
84 views

### Copula generation (Gaussian, t and Gumbel) with the help of correlation matrix using R

I have a set of data of 2 variates. I have generated correlation matrix between the variates. Using copula package of R, I computed t-copula using correlation ...
17 views

### Fitting a distribution for frequency

I have a list of objects and their frequencies of occurrence in R Names <- c("a","b","c","d","e") Freq <- c(12,45,67,100,1 ...) I want to rank the ...
218 views

### How do I fit a set of data to Burr Distribution in R?

For example I have a data set as: (2042.044,2218.153,3670.893,5149.684,5533.429,7111.183,11041.569,15459.771,783.477,1701.520,40810.770,67905.857) How do I fit the above data in Burr distribution to ...
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 ...
180 views

### Fit distributions with glm

I'm trying to fit different statistical distributions (Gamma, Poisson, normal, inverse Gaussian) to my data with a glm. An example could be like this: ...
103 views

### How fitting a mixture distribution of noncentral Student t components to a one-dimensional sample in R?

I`d like to extract the parameters of a two-component mixture distribution of noncentral student t distributions which first has to be fitted to a one-dimensional sample. My question is closely ...
87 views

### How does the sim() function in the arm package determine non-informative priors?

The arm package includes the sim() function. On its R help page it states: ...
53 views

### Significance of overlap between multiple lists

I am trying to evaluate the significance of overlap between several gene lists. Here I have applied different methods to select genes relevant to a disease and I have several 4 way venn diagrams ...
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### Compare two samples

similar questions have been asked but have not managed to get a conclusion from them. I am comparing two sets of samples, where ratios have been obtained for several analytes per sample. So the values ...
213 views

### Sampling data to have specific mean and standard deviation [duplicate]

I have a data that I want to sample such the resultant distribution of values should have specified mean and standard deviation. I can think of rejection sampling to achieve this however that seems to ...
139 views

### Non parametric Wilcoxon Signed Rank test

I have the following data vector(in fact its 2392 data points long): ...
149 views

### Estimating the distribution of a variable

I am trying to estimate (fit) the distribution of a variable. The first step in doing so is to draw a normal probability plot. This is what I have obtained (using R): ...
155 views

### R package fitdistrplus: function fitdist shows unusual error

I used the package R fitdistrplus in order to estimate parameters of different distribution function. In one case it shows a strange error message I can't interpret: ...
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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 ...
71 views

### Compare distributions with uneven and small sample sizes

I will be performing my analysis in R but any general mathematical-based answers will be appreciated. I realize similar questions have been asked before but I am new to statistics so please excuse my ...
162 views

### How to interpret log-likelihood outputs from MASS::fitdistr (R)

AIM: Fit the best distribution to columns in a dataset (30k records) so that I can to go on to produce test data that is in a similar distribution. WHAT I'VE DONE SO FAR: Using R, I have found and ...
408 views

### How to use the chi-squared test to determine if data follow the Poisson distribution

The figure below (Figure 1 from p. 646 of this paper) compares observed values against expected values under the Poisson distribution. It then runs a chi-squared test to see if the observed values ...
557 views

### What is quasibinomial?

I'm hoping someone can provide an intuitive overview of what quasibinomial is and what it does. I'm particularly interested in these points: How quasibinomial differs to the binomial distribution ...
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### Finding a suitable distribution for data in R? [duplicate]

I have a set of data with summary as below: The data are non-normal and transformations did not obtain normality. Given the data are continuous I have narrowed the range of distribution down to ...
184 views

### Sample from a custom continuous distribution in R

I have a probability density function in R and I want to draw a single sample from it. How do I do that? My current solution (and the one Google keeps giving me) is to evaluate the function for a ...
In the maximum likelihood estimation of Skew Normal, how does R calculate the mean? You know the formula is $$\mu=\frac{ \sum_{i} x_{i} W(x_{i})}{\sum_{i} W(x_{i})}$$. ...