# Tagged Questions

The Weibull distribution is a probability distribution with applications in survival analysis, reliability engineering, failure analysis, industrial engineering, extreme value theory, weather forecasting, forestry, and more.

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### Weibull Distribution v/s Gamma Distribution

What is the difference between the intuition behind Gamma and Weibull distributions? Is there any relationship between the two densities ? Kindly help.
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### Goodness of fit shows less than 0.01 p-values at all 16 distributions for my wind data

I have got two wind datasets (one for 4 months and the other one for 12 years). Typically wind speed distributions follow Weibull distributions. In order to demonstrate my data distribution in a ...
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### How can I test the difference of two Weibull distributions?

I have two Weibull distribution sets from two wind datasets in order to check whether they are same. I thought a 2 sample t-test would be applicable but I couldn't find any ways to do that on the ...
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### how can I compare two methods using weibull with unknown parameters and predictors

I would like to fit a weibull to a set of data. However, I dont have the suvival time of each data, but the total number. That means: I know that after 10 months 0.85 (n=500) are survived, after 20 ...
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### Difference powerlaw, lognormal and stretched exponential (Weibull) function

I am currently fitting above mentioned functions to my data and I can observe, that both lognormal and Weibull are better fits than a power-law. In the literature it is often suggested that it is hard ...
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### Right-censored survival fit with JAGS

Update: I got the JAGS model running and this eliminates the distracting part of my question. It's really about the proper preparation of data for dinterval() and inits. I can't find a concrete ...
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### Test for measuring pdf goodness of fit

The below picture represents a LiDAR cloud for an Eucalyptus spp plantation and the histogram is the density of "z" (height) values for a plot (there are several plots). The "x" axis is height in ...
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### How can I set up a JAGS model for linear regression with Weibull likelihood?

I am trying to set up a JAGS model for zero intercept linear regression using a Weibull likelihood. My data fit a Weibull distribution well, however, I don't have a good concept of the shape and scale ...
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### Fitting different models to my data in R

I have number of seeds fallen at different distances. I need to know which model fits these data, if any model does. There are different models that have been used to fit these data: negative ...
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### Weibull and Poisson proportional hazard test - survival data Stata

In a Cox model the proportional hazard model can be tested by for example: ...
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### Solving intercept / equivalence point / crossing point of where two Weibull regressions meet

I'm looking to solve the point where 2 opposite Weibull functions meet. I'm using the drc package, with a type 2 Weibull having 2 parameters in R. I've fit both ...
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### Weibull MLE: what is the method/algorithm used to perform the optimization?

Regarding fitting a Weibull two parameters probability density function (pdf), with the fitdistr from MASS package, in R: 1 - What is the iteration ...
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### Weibull distribution parameters $k$ and $c$ for wind speed data

I have 5 years worth of mean wind speed meteorological data. I want to compare the observed wind speed data against a Weibull distribution on a graph of the probability density distribution. I have ...
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### MLE: Two parameter or three parameter Weibull?

I would like to calculate the MLE estimates of the mean and variance of a Weibull distributional assumption, from a given sample. Now, there are two parameter and three parameter weibull ...
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### Weibull distribution - is it “heavy tailed” with three parameters?

I am fitting my data to Weibull distribution (I would like to prove, that they follow a power law). According to http://en.wikipedia.org/wiki/Heavy-tailed_distribution (and some articles), if "shape ...
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### Confidence intervals for extreme value distributions

I have wind data that i'm using to perform extreme value analysis (calculate return levels). I'm using R with packages 'evd', 'extRemes' and 'ismev'. I'm fitting GEV, Gumbel and Weibull ...
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### Weibull regression with known intercept in R

I'd like to run a Weibull regression with the pre-defined scale and shape parameters of the Weibull distribution. I'm using survreg() from ...
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### Accelerated Failure Time scale parameter excessively large when data is right censored

I am using an accelerated failure time model with the Weibull distribution to predict failure times. My failure times range from 1 - 365, with many (80%) data points that are right censored (no ...
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### Fitting a Weibull function in R

I am trying to model some data that follows a sigmoid curve relationship. In my field of work (psychophysics), a Weibull function is usually used to model such relationships, rather than probit. I am ...
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### How to interpret significant effects from a Weibull model when the Weibull assumption is met but the AFT/PH one is _not_

I have some survival data that I want to analyze (using survreg from the R survival package with the Weibull distribution). I ...
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### Mean survival time of a Weibull distribution

I'm trying to calculate the mean survival time of a Weibull distribution, and am getting what feels like an errant estimate of the mean--and each source I look up for how to calculate the mean gives a ...
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### Is there a multivariate version of the Weibull distribution?

I hope this one is self-explanatory, but let me know if something is unclear: Is there a multivariate version of the Weibull distribution?
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### How do I apply the method of moments for estimating parameters in a sum-relationship?

We have a model relationship between three random variables like this: $$U = C + S$$ I have a ton of measurements of realizations of $U$, as well as a ton of realizations of $C$. But the ...
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### Elementary treatment of the Weibull distribution

I am looking for a reference to an elementary (or at least fairly simple) treatment of the Weibull-distribution. I have a bright high school student doing a project on wind mills and it turns out that ...
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### Route to understanding and implementing statistical timing models

The research paper Forecasting NBA Player Performance by Douglas Hwang describes a method for predicting player performance by utilizing a statistical timing model and a 'Weibull-Gamma' distribution. ...
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### Conjugate of Weibull with shape known

This isn't exactly a homework problem but rather a self-selected problem I'm doing to prepare for a midterm. I can see from Wikipedia that it is an inverse gamma but I am unable to reach the ...
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### Which R package for estimating a multilevel Weibull regression model?

Could you recommend an R package for estimating a (frequentist) multilevel Weibull regression model? I need to model random intercepts, random slopes, as well as a cross-classified structure. ...
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### Can I use a Z-score with skewed and non-normal data?

I've been working with some process cycle time data and scaling using the standard z-score in order to compare between parts of the full cycle time. Should I use some other transformation since the ...
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### Weibull distributed data for correlation analysis

On visual inspection of P-P plots, my time data appears to fit a Weibull distribution better than a normal distribution. I will use the variable for correlations and as a predictor in regression. In ...
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### Adjustment coefficient (Lundberg coefficient) for a Weibull distribution

I am very glad that I have found this community and I wanted, beforehand, to thank anyone reading my post. I appreciate that very much! I am estimating the ruin probability for Weibull (in the light ...
Note: I am posting a question from a former student of mine unable to post on his own for technical reasons. Given an iid sample $x_1,\ldots,x_n$ from a Weibull distribution with pdf  f(x) = k ...