Compute the maximum likelihood estimator for $θ$.












0












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Let $X_1, X_2, . . . , X_n$ be a random sample from a Bernoulli distribution with parameter $θ$. Compute the maximum likelihood estimator for $θ$.



In my opinion this is the correct way to solve it:
$L(Theta)=theta_1*(1-theta_1)*...theta_n*(1-theta_n)=theta^n*(1-theta)^n$
$l(Theta)=n*ln(theta)+n*ln(1-theta)$
$l'(theta)=frac{n}{theta}-frac{n}{1-theta}=0$, $theta=frac{1}{2}$

For the official solution it should be $frac{sum_{i=1}^nX_i}{n}$, why MLE is incorrect, where should I put the $x$ that in my solution is not present?










share|cite|improve this question









$endgroup$








  • 1




    $begingroup$
    bernoulli has no pdf, calculating max with derivatives is here not possible
    $endgroup$
    – Joey Doey
    Jan 25 at 14:52








  • 1




    $begingroup$
    Your likelihood formula is wrong - your formula doesn't depend on the data that you see, only $n$. When you use the correct formula you can differentiate the log likelihood to get the MLE.
    $endgroup$
    – Alex
    Jan 25 at 15:28










  • $begingroup$
    @Alex what do you mean?
    $endgroup$
    – Luke Marci
    Jan 25 at 15:31






  • 1




    $begingroup$
    The likelihood should depend on the data you see. E.g. suppose you just had $n = 1$ and observed $X_1 = x_1$. If that was a success ($x_1 = 1$) then the likelihood would be $theta$, and if it was a failure ($x_1 = 0$) then the likelihood would be $(1 - theta)$. In the first case the MLE would be $hat{theta} = 1$ and in the second case the MLE would be $hat{theta} = 0$.
    $endgroup$
    – Alex
    Jan 25 at 15:36


















0












$begingroup$


Let $X_1, X_2, . . . , X_n$ be a random sample from a Bernoulli distribution with parameter $θ$. Compute the maximum likelihood estimator for $θ$.



In my opinion this is the correct way to solve it:
$L(Theta)=theta_1*(1-theta_1)*...theta_n*(1-theta_n)=theta^n*(1-theta)^n$
$l(Theta)=n*ln(theta)+n*ln(1-theta)$
$l'(theta)=frac{n}{theta}-frac{n}{1-theta}=0$, $theta=frac{1}{2}$

For the official solution it should be $frac{sum_{i=1}^nX_i}{n}$, why MLE is incorrect, where should I put the $x$ that in my solution is not present?










share|cite|improve this question









$endgroup$








  • 1




    $begingroup$
    bernoulli has no pdf, calculating max with derivatives is here not possible
    $endgroup$
    – Joey Doey
    Jan 25 at 14:52








  • 1




    $begingroup$
    Your likelihood formula is wrong - your formula doesn't depend on the data that you see, only $n$. When you use the correct formula you can differentiate the log likelihood to get the MLE.
    $endgroup$
    – Alex
    Jan 25 at 15:28










  • $begingroup$
    @Alex what do you mean?
    $endgroup$
    – Luke Marci
    Jan 25 at 15:31






  • 1




    $begingroup$
    The likelihood should depend on the data you see. E.g. suppose you just had $n = 1$ and observed $X_1 = x_1$. If that was a success ($x_1 = 1$) then the likelihood would be $theta$, and if it was a failure ($x_1 = 0$) then the likelihood would be $(1 - theta)$. In the first case the MLE would be $hat{theta} = 1$ and in the second case the MLE would be $hat{theta} = 0$.
    $endgroup$
    – Alex
    Jan 25 at 15:36
















0












0








0





$begingroup$


Let $X_1, X_2, . . . , X_n$ be a random sample from a Bernoulli distribution with parameter $θ$. Compute the maximum likelihood estimator for $θ$.



In my opinion this is the correct way to solve it:
$L(Theta)=theta_1*(1-theta_1)*...theta_n*(1-theta_n)=theta^n*(1-theta)^n$
$l(Theta)=n*ln(theta)+n*ln(1-theta)$
$l'(theta)=frac{n}{theta}-frac{n}{1-theta}=0$, $theta=frac{1}{2}$

For the official solution it should be $frac{sum_{i=1}^nX_i}{n}$, why MLE is incorrect, where should I put the $x$ that in my solution is not present?










share|cite|improve this question









$endgroup$




Let $X_1, X_2, . . . , X_n$ be a random sample from a Bernoulli distribution with parameter $θ$. Compute the maximum likelihood estimator for $θ$.



In my opinion this is the correct way to solve it:
$L(Theta)=theta_1*(1-theta_1)*...theta_n*(1-theta_n)=theta^n*(1-theta)^n$
$l(Theta)=n*ln(theta)+n*ln(1-theta)$
$l'(theta)=frac{n}{theta}-frac{n}{1-theta}=0$, $theta=frac{1}{2}$

For the official solution it should be $frac{sum_{i=1}^nX_i}{n}$, why MLE is incorrect, where should I put the $x$ that in my solution is not present?







statistics






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Jan 25 at 14:49









Luke MarciLuke Marci

856




856








  • 1




    $begingroup$
    bernoulli has no pdf, calculating max with derivatives is here not possible
    $endgroup$
    – Joey Doey
    Jan 25 at 14:52








  • 1




    $begingroup$
    Your likelihood formula is wrong - your formula doesn't depend on the data that you see, only $n$. When you use the correct formula you can differentiate the log likelihood to get the MLE.
    $endgroup$
    – Alex
    Jan 25 at 15:28










  • $begingroup$
    @Alex what do you mean?
    $endgroup$
    – Luke Marci
    Jan 25 at 15:31






  • 1




    $begingroup$
    The likelihood should depend on the data you see. E.g. suppose you just had $n = 1$ and observed $X_1 = x_1$. If that was a success ($x_1 = 1$) then the likelihood would be $theta$, and if it was a failure ($x_1 = 0$) then the likelihood would be $(1 - theta)$. In the first case the MLE would be $hat{theta} = 1$ and in the second case the MLE would be $hat{theta} = 0$.
    $endgroup$
    – Alex
    Jan 25 at 15:36
















  • 1




    $begingroup$
    bernoulli has no pdf, calculating max with derivatives is here not possible
    $endgroup$
    – Joey Doey
    Jan 25 at 14:52








  • 1




    $begingroup$
    Your likelihood formula is wrong - your formula doesn't depend on the data that you see, only $n$. When you use the correct formula you can differentiate the log likelihood to get the MLE.
    $endgroup$
    – Alex
    Jan 25 at 15:28










  • $begingroup$
    @Alex what do you mean?
    $endgroup$
    – Luke Marci
    Jan 25 at 15:31






  • 1




    $begingroup$
    The likelihood should depend on the data you see. E.g. suppose you just had $n = 1$ and observed $X_1 = x_1$. If that was a success ($x_1 = 1$) then the likelihood would be $theta$, and if it was a failure ($x_1 = 0$) then the likelihood would be $(1 - theta)$. In the first case the MLE would be $hat{theta} = 1$ and in the second case the MLE would be $hat{theta} = 0$.
    $endgroup$
    – Alex
    Jan 25 at 15:36










1




1




$begingroup$
bernoulli has no pdf, calculating max with derivatives is here not possible
$endgroup$
– Joey Doey
Jan 25 at 14:52






$begingroup$
bernoulli has no pdf, calculating max with derivatives is here not possible
$endgroup$
– Joey Doey
Jan 25 at 14:52






1




1




$begingroup$
Your likelihood formula is wrong - your formula doesn't depend on the data that you see, only $n$. When you use the correct formula you can differentiate the log likelihood to get the MLE.
$endgroup$
– Alex
Jan 25 at 15:28




$begingroup$
Your likelihood formula is wrong - your formula doesn't depend on the data that you see, only $n$. When you use the correct formula you can differentiate the log likelihood to get the MLE.
$endgroup$
– Alex
Jan 25 at 15:28












$begingroup$
@Alex what do you mean?
$endgroup$
– Luke Marci
Jan 25 at 15:31




$begingroup$
@Alex what do you mean?
$endgroup$
– Luke Marci
Jan 25 at 15:31




1




1




$begingroup$
The likelihood should depend on the data you see. E.g. suppose you just had $n = 1$ and observed $X_1 = x_1$. If that was a success ($x_1 = 1$) then the likelihood would be $theta$, and if it was a failure ($x_1 = 0$) then the likelihood would be $(1 - theta)$. In the first case the MLE would be $hat{theta} = 1$ and in the second case the MLE would be $hat{theta} = 0$.
$endgroup$
– Alex
Jan 25 at 15:36






$begingroup$
The likelihood should depend on the data you see. E.g. suppose you just had $n = 1$ and observed $X_1 = x_1$. If that was a success ($x_1 = 1$) then the likelihood would be $theta$, and if it was a failure ($x_1 = 0$) then the likelihood would be $(1 - theta)$. In the first case the MLE would be $hat{theta} = 1$ and in the second case the MLE would be $hat{theta} = 0$.
$endgroup$
– Alex
Jan 25 at 15:36












1 Answer
1






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$begingroup$

The likelihood function for Bernoulli can be written as follows:
$$
L(theta)=begin{cases}theta, & X_1=1cr 1-theta, & X_1=0end{cases}times begin{cases}theta, & X_2=1cr 1-theta, & X_2=0end{cases}times cdotstimesbegin{cases}theta, & X_n=1cr 1-theta, & X_n=0end{cases}
$$

Note that $sum_{i=1}^n X_i=noverline X$ calculates the number of units in a sample, and $n-noverline X$ calculates the number of zeros. In the above product, $theta$ is multiplied as many times as there are units in the sample. And $1-theta$ is multiplied as many times as there are zeros in the sample. So
$$
L(theta) = theta^{noverline X}cdot (1-theta)^{n-noverline X}.
$$

Starting from here you can calculate MLE with derivatives.






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    $begingroup$

    The likelihood function for Bernoulli can be written as follows:
    $$
    L(theta)=begin{cases}theta, & X_1=1cr 1-theta, & X_1=0end{cases}times begin{cases}theta, & X_2=1cr 1-theta, & X_2=0end{cases}times cdotstimesbegin{cases}theta, & X_n=1cr 1-theta, & X_n=0end{cases}
    $$

    Note that $sum_{i=1}^n X_i=noverline X$ calculates the number of units in a sample, and $n-noverline X$ calculates the number of zeros. In the above product, $theta$ is multiplied as many times as there are units in the sample. And $1-theta$ is multiplied as many times as there are zeros in the sample. So
    $$
    L(theta) = theta^{noverline X}cdot (1-theta)^{n-noverline X}.
    $$

    Starting from here you can calculate MLE with derivatives.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      The likelihood function for Bernoulli can be written as follows:
      $$
      L(theta)=begin{cases}theta, & X_1=1cr 1-theta, & X_1=0end{cases}times begin{cases}theta, & X_2=1cr 1-theta, & X_2=0end{cases}times cdotstimesbegin{cases}theta, & X_n=1cr 1-theta, & X_n=0end{cases}
      $$

      Note that $sum_{i=1}^n X_i=noverline X$ calculates the number of units in a sample, and $n-noverline X$ calculates the number of zeros. In the above product, $theta$ is multiplied as many times as there are units in the sample. And $1-theta$ is multiplied as many times as there are zeros in the sample. So
      $$
      L(theta) = theta^{noverline X}cdot (1-theta)^{n-noverline X}.
      $$

      Starting from here you can calculate MLE with derivatives.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        The likelihood function for Bernoulli can be written as follows:
        $$
        L(theta)=begin{cases}theta, & X_1=1cr 1-theta, & X_1=0end{cases}times begin{cases}theta, & X_2=1cr 1-theta, & X_2=0end{cases}times cdotstimesbegin{cases}theta, & X_n=1cr 1-theta, & X_n=0end{cases}
        $$

        Note that $sum_{i=1}^n X_i=noverline X$ calculates the number of units in a sample, and $n-noverline X$ calculates the number of zeros. In the above product, $theta$ is multiplied as many times as there are units in the sample. And $1-theta$ is multiplied as many times as there are zeros in the sample. So
        $$
        L(theta) = theta^{noverline X}cdot (1-theta)^{n-noverline X}.
        $$

        Starting from here you can calculate MLE with derivatives.






        share|cite|improve this answer









        $endgroup$



        The likelihood function for Bernoulli can be written as follows:
        $$
        L(theta)=begin{cases}theta, & X_1=1cr 1-theta, & X_1=0end{cases}times begin{cases}theta, & X_2=1cr 1-theta, & X_2=0end{cases}times cdotstimesbegin{cases}theta, & X_n=1cr 1-theta, & X_n=0end{cases}
        $$

        Note that $sum_{i=1}^n X_i=noverline X$ calculates the number of units in a sample, and $n-noverline X$ calculates the number of zeros. In the above product, $theta$ is multiplied as many times as there are units in the sample. And $1-theta$ is multiplied as many times as there are zeros in the sample. So
        $$
        L(theta) = theta^{noverline X}cdot (1-theta)^{n-noverline X}.
        $$

        Starting from here you can calculate MLE with derivatives.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 26 at 3:47









        NChNCh

        6,8753825




        6,8753825






























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