weibull

Hello, I'm very new to statistics and ran into a problem that I don't know the answer to. I want to do a capability analysis, but my data set is not normally distributed, so I transformed it using the Johnson transform in Minitab. Now I had a normal distribution and very good CP, CPK values...

Hello, I fitted a Weibull Accelerated Failure Time (AFT) to my dataset (n=1071). The output reported the shape parameter (B=0.67,p<0.001). My understanding is that since the coefficient is less than 1, this means that the hazard is increasing over time. Is this correct? I also fitted another...

Hello, I'm looking for a formula that accounts for a timeshift that is distributed (weibull/lognormal) For example. I have "hits" that fall into a week. W1: 1 1 1 1 1 1 Total hits W1=6 W2: 1 1 1 1 Total hits W2=4 W3: 1 1 1 1 1 Total hits W3=5 W4: 1 1 1 1 1 1 1 Total hits W4=7 Each week is...

Hello there First of all I am not a pure statistician, however I worked with Weibull stats during my PhD. Now that I am working in marketing, I realized that "customers' orders" can be modeled with Weibull (someone can argue: what can't be modeled with Weibull?!?... Weibull is life!). In...

Hello, I would be very grateful if someone could tell me if my application of the Weibull function to my data is correct or not. (The question is very simple, but requires a bit of background information, so please bear with me!) Please find below a few background details about my study: - I...

I have a data which is the interval days of customers purchasing products. I try to estimate the shape and scale params by scipy.stat.weibull_min But, the parameters returned from the fit function is not unique and when I try to constrain the scale param to be 1, it does not work. Here is the...

Hi, I know that the formula for computing the raw moments of 2-parameter Weibull distribution is: Mu'n=b^n*Gamma(1+n/c), where b and c are scale and shape parameters, respectively. However, I couldn't find any exact formula for a 3-parameter Weibull distribution. Is there any simple formula...

I have got a set of wind speed data for weibull analysis. And I need to calculate root mean square error (RMSE) for statistical test.How do I calculate it?

I am doing project in which I need to estimate weibull parameters for car part failures ( I know data follows weibull ). I have 1000 cars data (part failure data). Now the problem is suppose some part fails after 6 year( from date of manufacturing) . But i have data of only first three year. Now...

I am currently fitting above mentioned functions to my data and I can observe, that both lognormal and Weibull are better fits than powerlaw. In literature, it is often suggested, that it is hard to distinguish these functions, but I can in my data. I do not completely understand the...

Hi, Can any one tell me how to fit some data with zero's to a weibull fit using Matlab. I tried using Maximum Likelihood Estimator and wbfit. But I am experiencing problem because of zero's. It requires positive values. Thank you very much Vinay

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Hi, I have life data which contains time to failures of zero, I'm really not sure which distribution I should use to analyse this data, i've tried using a weibull distribution in software such as mintab and Weibull++ but they either ignore the data when calculating the parameters or do not...

I was wondering what methods you can use if you are trying to predict failure in a product. I have a product and the following information about the product: 1. The date it was produced 2. number of products produced in the lot 3. The number of products purchased out of that lot 4...

Good Morning, This is the first time that I have posted anything and I am really in need of guidance. I am trying to figure out the best way to predict failure using warranty data. I have a product that had very few claims in the beginning, but the longer the life of the product the...

How do i implement lifereg or generate a weibull distribution for this kind of data? Time (Mins) Cumulative % Failure 0-30 4 30-60 10 60-90 15 90-120 18 120-150 22 150-180...