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https://community.wolfram.com/groups/-/m/t/2174471
&[Wolfram Notebook][1]
[1]: https://www.wolframcloud.com/obj/33d543ff-cefe-4461-866b-3b3436833330Pedro Cabral2021-01-26T01:52:51ZStrange PDF of BinomialDistribution
https://community.wolfram.com/groups/-/m/t/2164818
PDF[BinomialDistribution[1,.5],{0,0.5,1}]
gives {0.5,0.63662,0.5}
and
PDF[BernoulliDistribution[.5],{0,0.5,1}]
gives {0.5,0,0.5}.
Obviously, `BinomialDistribution[1,.5]` and `BernoulliDistribution[.5]` are the same.Stefan Huschens2021-01-16T13:30:03ZCalculation of variance of weighted data
https://community.wolfram.com/groups/-/m/t/2172718
The WDC example ([/Scope/Data][2]: "Find the variance of WeightedData") merges the internal intermediary result (of the mean) and shows the end result in a single line only, so i cannot back track anymore.
Inspired by that WDC example, please could anyone demonstrate how the $\frac{8800}{23}$ was calculated (just the start/from which definition)? Feel free to use two lines: 1 line for the numeric mean, 1 for the variance using that numeric mean.
In[1]:= data = {-30, 10, 10, 10, 10, 10, 10, 10, 20, 20};(* sample data *)
{Mean[data], Variance[data]}(* bias-corrected sample variance*)
Out[2]= {8, 1760/9}
In[3]:= edis = EmpiricalDistribution[data];(* population *)
{Mean[edis], Variance[edis]}(* population variance *)
Out[4]= {8, 176}
In[5]:= wdata = WeightedData[{-30, 10, 20}, {1/10, 7/10, 2/10}];
wedis = EmpiricalDistribution[wdata];
{Mean[wedis], Variance[wedis]}(* okay,as expected *)
Out[7]= {8, 176}
In[8]:= {Mean[wdata], Variance[wdata]}(* which formula/definition used here, why? *)
Out[8]= {8, 8800/23}
I cannot figure it out, thank you! Best wishes.
[2]: https://reference.wolfram.com/language/ref/Variance.htmlRaspi Rascal2021-01-24T18:34:40ZVARIANCE and PDF
https://community.wolfram.com/groups/-/m/t/2169540
Hello all,
I am struggling to find the correct function for Variance. It does exist, but it is the SAMPLE variance, i.e. the (n-1) denominator.
I need to find (if it does exist) the SIGMA variance, i.e. the one with just N at the denominator.
Anyone knows ?
Plus, suppose I wanted to plot the pdf f(x) =ce^-x (0<x<1) and find the CDF and its expected value. How would I proceed?
Thank you all.Mauro Benjamin Mistretta2021-01-21T19:50:36Z