Distribution that works with positive and negative skewness

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Anel Ruiz
Anel Ruiz 2020-6-16
回答： Jeff Miller 2020-6-18
Hi,
I am trying to obtain the distribution type of a variable that changes over time. For each stage I have n number of data.
I use fitdist grouping by stage to get the distribution for each stage. The problem is that the distribution varies over time, being, in some stages, positive skewed (lognormal is the best distribution), in other stages symetrical (normal) and in other stages negative skewed (extreme value).
My question is if there is any distribution type that fits for all cases; and if there is not, how can I change the distribution type by stage as fitdist only allow one distribution type.
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Anel Ruiz
Anel Ruiz 2020-6-16
Aditional, I would appreciate any alternative advise for analysing this kind of data. I thought of only use median and percentiles, but I'am still trying with distribution types.

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采纳的回答

Jeff Miller
Jeff Miller 2020-6-18
The skew normal is in Cupid. The last parameter controls the amount and direction of skew. E.g.,
posSkew = SkewNor(10,1,2);
posSkew.PlotDens;
negSkew = SkewNor(10,1,-2);
negSkew.PlotDens;

更多回答（1 个）

Image Analyst
Image Analyst 2020-6-16
Did you see the skewed normal distribution:
https://en.wikipedia.org/wiki/Skew_normal_distribution
  2 个评论
Image Analyst
Image Analyst 2020-6-18
Not sure. Probably not. random() has a few dozen distributions -- would one of them work for you?

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