Compute the Mean Squared Error of $𝑇$












2












$begingroup$


The famous biologist Henk de Rijn has come up with a skill test for chimpanzees.
We assume that each chimpanzee has a probability $𝑝$ to pass the test, independent from previous attempts and from other monkeys.
Let $𝑋_𝑖$ be the number of attempts that chimpanzee $𝑖$ needs to pass. Furthermore, $𝑇 = overline{X}_𝑛$ is an estimator for $1/𝑝$.
Compute the mean squared error of $𝑇$ .



So let $T$ be an estimator for a parameter $1∕𝑝$. The $MSE$ of $T$ is $MSE(T)=operatorname{Var}(T) + (E[T] − 1∕𝑝)^2$, where$(E[T] − 1∕𝑝)^2$ is the bias.

In this case the $E[T]=E[overline{X}_𝑛]=mu$ and $operatorname{Var}(T)=operatorname{Var}(overline{X}_𝑛)=dfrac{sigma^2}{n}$.

Now my question is: which distribution should I use?

I think that I think that is a Binomial but it also make sense to use a Geometric Distribution, so then the estimator $T$ will be unbiased and the $displaystyleoperatorname{MSE}(T)=operatorname{Var}(T)=frac{1-p}{p^2}*frac{1}{n}$, is it right?










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  • 1




    $begingroup$
    Here's what I see.
    $endgroup$
    – Shaun
    Jan 23 at 22:29












  • $begingroup$
    Strange, I see all the value inside the dollars
    $endgroup$
    – Luke Marci
    Jan 24 at 8:19
















2












$begingroup$


The famous biologist Henk de Rijn has come up with a skill test for chimpanzees.
We assume that each chimpanzee has a probability $𝑝$ to pass the test, independent from previous attempts and from other monkeys.
Let $𝑋_𝑖$ be the number of attempts that chimpanzee $𝑖$ needs to pass. Furthermore, $𝑇 = overline{X}_𝑛$ is an estimator for $1/𝑝$.
Compute the mean squared error of $𝑇$ .



So let $T$ be an estimator for a parameter $1∕𝑝$. The $MSE$ of $T$ is $MSE(T)=operatorname{Var}(T) + (E[T] − 1∕𝑝)^2$, where$(E[T] − 1∕𝑝)^2$ is the bias.

In this case the $E[T]=E[overline{X}_𝑛]=mu$ and $operatorname{Var}(T)=operatorname{Var}(overline{X}_𝑛)=dfrac{sigma^2}{n}$.

Now my question is: which distribution should I use?

I think that I think that is a Binomial but it also make sense to use a Geometric Distribution, so then the estimator $T$ will be unbiased and the $displaystyleoperatorname{MSE}(T)=operatorname{Var}(T)=frac{1-p}{p^2}*frac{1}{n}$, is it right?










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    Here's what I see.
    $endgroup$
    – Shaun
    Jan 23 at 22:29












  • $begingroup$
    Strange, I see all the value inside the dollars
    $endgroup$
    – Luke Marci
    Jan 24 at 8:19














2












2








2





$begingroup$


The famous biologist Henk de Rijn has come up with a skill test for chimpanzees.
We assume that each chimpanzee has a probability $𝑝$ to pass the test, independent from previous attempts and from other monkeys.
Let $𝑋_𝑖$ be the number of attempts that chimpanzee $𝑖$ needs to pass. Furthermore, $𝑇 = overline{X}_𝑛$ is an estimator for $1/𝑝$.
Compute the mean squared error of $𝑇$ .



So let $T$ be an estimator for a parameter $1∕𝑝$. The $MSE$ of $T$ is $MSE(T)=operatorname{Var}(T) + (E[T] − 1∕𝑝)^2$, where$(E[T] − 1∕𝑝)^2$ is the bias.

In this case the $E[T]=E[overline{X}_𝑛]=mu$ and $operatorname{Var}(T)=operatorname{Var}(overline{X}_𝑛)=dfrac{sigma^2}{n}$.

Now my question is: which distribution should I use?

I think that I think that is a Binomial but it also make sense to use a Geometric Distribution, so then the estimator $T$ will be unbiased and the $displaystyleoperatorname{MSE}(T)=operatorname{Var}(T)=frac{1-p}{p^2}*frac{1}{n}$, is it right?










share|cite|improve this question











$endgroup$




The famous biologist Henk de Rijn has come up with a skill test for chimpanzees.
We assume that each chimpanzee has a probability $𝑝$ to pass the test, independent from previous attempts and from other monkeys.
Let $𝑋_𝑖$ be the number of attempts that chimpanzee $𝑖$ needs to pass. Furthermore, $𝑇 = overline{X}_𝑛$ is an estimator for $1/𝑝$.
Compute the mean squared error of $𝑇$ .



So let $T$ be an estimator for a parameter $1∕𝑝$. The $MSE$ of $T$ is $MSE(T)=operatorname{Var}(T) + (E[T] − 1∕𝑝)^2$, where$(E[T] − 1∕𝑝)^2$ is the bias.

In this case the $E[T]=E[overline{X}_𝑛]=mu$ and $operatorname{Var}(T)=operatorname{Var}(overline{X}_𝑛)=dfrac{sigma^2}{n}$.

Now my question is: which distribution should I use?

I think that I think that is a Binomial but it also make sense to use a Geometric Distribution, so then the estimator $T$ will be unbiased and the $displaystyleoperatorname{MSE}(T)=operatorname{Var}(T)=frac{1-p}{p^2}*frac{1}{n}$, is it right?







statistics






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share|cite|improve this question













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share|cite|improve this question








edited Jan 23 at 21:33









Adrian Keister

5,27371933




5,27371933










asked Jan 23 at 21:27









Luke MarciLuke Marci

856




856








  • 1




    $begingroup$
    Here's what I see.
    $endgroup$
    – Shaun
    Jan 23 at 22:29












  • $begingroup$
    Strange, I see all the value inside the dollars
    $endgroup$
    – Luke Marci
    Jan 24 at 8:19














  • 1




    $begingroup$
    Here's what I see.
    $endgroup$
    – Shaun
    Jan 23 at 22:29












  • $begingroup$
    Strange, I see all the value inside the dollars
    $endgroup$
    – Luke Marci
    Jan 24 at 8:19








1




1




$begingroup$
Here's what I see.
$endgroup$
– Shaun
Jan 23 at 22:29






$begingroup$
Here's what I see.
$endgroup$
– Shaun
Jan 23 at 22:29














$begingroup$
Strange, I see all the value inside the dollars
$endgroup$
– Luke Marci
Jan 24 at 8:19




$begingroup$
Strange, I see all the value inside the dollars
$endgroup$
– Luke Marci
Jan 24 at 8:19










1 Answer
1






active

oldest

votes


















1












$begingroup$

Each $X_i$ follows a Geometric distribution.



ie $X_i ~ Geom(p)$, and $T=frac{X_1+...+X_n}{n}$, and the $X_i$s are independent and identically distributed, ie $E(T)=frac{1}{p}$.
Therefore, $MSE(T)$ is just $Var(T)$, and since the variance of a sum is the sum of the variances when dealing with independent random variables, then $Var(T)=Var(frac{X_1+...+X_n}{n})=frac{1}{n^2}$$(Var(X_1)+...+Var(X_n))=frac{1}{n}frac{p}{(1-p)^2}$.



So yes, it is correct.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    The Variance for a geometric distribution is not $frac{1-p}{p^2}$?
    $endgroup$
    – Luke Marci
    Jan 24 at 8:30











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1 Answer
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1 Answer
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active

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1












$begingroup$

Each $X_i$ follows a Geometric distribution.



ie $X_i ~ Geom(p)$, and $T=frac{X_1+...+X_n}{n}$, and the $X_i$s are independent and identically distributed, ie $E(T)=frac{1}{p}$.
Therefore, $MSE(T)$ is just $Var(T)$, and since the variance of a sum is the sum of the variances when dealing with independent random variables, then $Var(T)=Var(frac{X_1+...+X_n}{n})=frac{1}{n^2}$$(Var(X_1)+...+Var(X_n))=frac{1}{n}frac{p}{(1-p)^2}$.



So yes, it is correct.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    The Variance for a geometric distribution is not $frac{1-p}{p^2}$?
    $endgroup$
    – Luke Marci
    Jan 24 at 8:30
















1












$begingroup$

Each $X_i$ follows a Geometric distribution.



ie $X_i ~ Geom(p)$, and $T=frac{X_1+...+X_n}{n}$, and the $X_i$s are independent and identically distributed, ie $E(T)=frac{1}{p}$.
Therefore, $MSE(T)$ is just $Var(T)$, and since the variance of a sum is the sum of the variances when dealing with independent random variables, then $Var(T)=Var(frac{X_1+...+X_n}{n})=frac{1}{n^2}$$(Var(X_1)+...+Var(X_n))=frac{1}{n}frac{p}{(1-p)^2}$.



So yes, it is correct.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    The Variance for a geometric distribution is not $frac{1-p}{p^2}$?
    $endgroup$
    – Luke Marci
    Jan 24 at 8:30














1












1








1





$begingroup$

Each $X_i$ follows a Geometric distribution.



ie $X_i ~ Geom(p)$, and $T=frac{X_1+...+X_n}{n}$, and the $X_i$s are independent and identically distributed, ie $E(T)=frac{1}{p}$.
Therefore, $MSE(T)$ is just $Var(T)$, and since the variance of a sum is the sum of the variances when dealing with independent random variables, then $Var(T)=Var(frac{X_1+...+X_n}{n})=frac{1}{n^2}$$(Var(X_1)+...+Var(X_n))=frac{1}{n}frac{p}{(1-p)^2}$.



So yes, it is correct.






share|cite|improve this answer









$endgroup$



Each $X_i$ follows a Geometric distribution.



ie $X_i ~ Geom(p)$, and $T=frac{X_1+...+X_n}{n}$, and the $X_i$s are independent and identically distributed, ie $E(T)=frac{1}{p}$.
Therefore, $MSE(T)$ is just $Var(T)$, and since the variance of a sum is the sum of the variances when dealing with independent random variables, then $Var(T)=Var(frac{X_1+...+X_n}{n})=frac{1}{n^2}$$(Var(X_1)+...+Var(X_n))=frac{1}{n}frac{p}{(1-p)^2}$.



So yes, it is correct.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Jan 23 at 21:56









AlexandrosAlexandros

9401412




9401412












  • $begingroup$
    The Variance for a geometric distribution is not $frac{1-p}{p^2}$?
    $endgroup$
    – Luke Marci
    Jan 24 at 8:30


















  • $begingroup$
    The Variance for a geometric distribution is not $frac{1-p}{p^2}$?
    $endgroup$
    – Luke Marci
    Jan 24 at 8:30
















$begingroup$
The Variance for a geometric distribution is not $frac{1-p}{p^2}$?
$endgroup$
– Luke Marci
Jan 24 at 8:30




$begingroup$
The Variance for a geometric distribution is not $frac{1-p}{p^2}$?
$endgroup$
– Luke Marci
Jan 24 at 8:30


















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