使泊松分布适合数据 [英] Fit poisson distribution to data

问题描述

我已经绘制了直方图，并希望将泊松分布拟合到直方图.为此，我已将x和y直方图坐标向量传递给poissfit()函数以估计lambda.

I have plotted a histogram and would like to fit a poisson distribution to the histogram. To do this, I have passed the x and y histogram coordinate vector to the poissfit() function to estimate lambda.

例如，这是我所做的:

expecteddata = cat(2,x,y)
[l,lci] = poissfit(expecteddata)

我的输出看起来像这样:

My output looks like so:

l =

   44.3766    0.0130


lci =

   42.8887    0.0003
   45.8645    0.0724

我假设对绘制感兴趣的lambda为0.013(我认为我的lambda很小，因为我的直方图是频率直方图).我使用以下方法绘制了泊松pdf格式:

I'm assuming the the lambda I'm interested in for plotting would be 0.013 (I think my lambda is so small because my histogram is a frequency histogram). I plot the poisson pdf using:

x = 0:50
y = poisspdf(x,0.013);
plot(x,y,'r')

然后我得到了结果叠加图:

And I get the resulting overlayed plot:

但是，我认为这种合适的分布看起来有些奇怪.它似乎不是很泊松"样.有人知道我做错了什么吗?

However, I think this fitted distribution looks a little odd. It doesn't appear to be very "poisson" like. Does anyone know if I'm doing anything incorrectly?

推荐答案

我已经绘制了直方图，并希望将泊松分布拟合到直方图."

"I have plotted a histogram and would like to fit a poisson distribution to the histogram."

我了解的是，您需要将泊松分布与现有的测量数据直方图拟合.我相信您可以使用fitdist()函数.

What I understand is you need to fit poisson distribution to a existing histogram of measured data. I believe you can use the fitdist() function.

例如，如果您的数据是x.

For example, if your data is x.

[n,bin]=hist(x,100);
m=n/trapz(bin,n);
bar(bin,m,'w');
hold on
pd=fitdist(x,'poisson');
y=pdf(pd,bin);
plot(bin,y,'k');
hold off;

将为您提供一个具有泊松分布曲线的直方图.

will give you a histogram with a poisson distributed curve fitted to it.

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