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Next: $B%5%$%1%X%O%/%/!&(B Up: $Beb%1ecBe$&eb%Cn7%"p*0e&$ec.e&-ie!&qv(B/A> Previous: $B%9%Q%$%/L)EY?dDj(B   $BL\   $B:w0z(B

$Bh#(B $BE}7WE*?dB,(B

$BE}7WE*?dB,$NM}O@$HZ$K;H$&$3$H$r?d?J$7$?!%%U%#%C%7%c!<$O%G!<%?$+$iF@$i$l$kE}7WNL$HE}7W%b%G%k$NJl?t$H$rL@3N$K6hJL$7!$E}7WNL!J?dDjNL!K$NK>$^$7$$@-Dj$O!$Jl?t$,Dj?t$G$"$k$3$H$G$"$k!%(B $B7WB,4|4VCf$KJl?t$,JQF0$7$?$j!$;n9T$4$H$KJl?t$,JQF0$9$k$3$H$OA[Dj$7$J$$!%?@7P2J3X$K$*$1$k$$F10l


$BJ?6QFs>h8m:9(B

$ \hat{\theta}$ $B$r%Q%i%a!<%?(B$ \theta$ $B$N?dDjNL$H$9$k!%Nc$r$"$2$F$_$h$&!%(B$ X_{i}$ $B$,J?6Q(B$ \theta$ $B$N;X?tJ,I[$K=>$&Mp?t$H$9$k$H!$(B$ \theta$ $B$N?dDjNL(B $ \hat{\theta}$ $B$NNc$H$7$F$^$:9M$($i$l$k$N$,!$J?6Q(B $ \hat
{\theta}_{n}=\frac{1}{n}\sum X_{i}$ $B!$$,$"$k!%?dDjNL$OB>$K$b9M$($i$l$k!%Nc$($P=i$a$N%5%s%W%k$@$1$r;H$&(B $ \hat{\theta}_{1}=X_{i}$ $B$b(B$ \theta$ $B$N?dDjNL$G$"$k!%$=$l$G$OK>$^$7$$?dDjNL$H$O$I$N$h$&$J@-h8m:9$O$=$N0l$D$N4p=`$rM?$($k$H9M$($i$l$k!%(B

MSE$\displaystyle =E[(\hat{\theta}-\theta)^{2}]%
$ (4.1)

$BFs>hB;<:4X?t!"B;<:4X?t$r??$NJ,I[$G4|BTCM$r$H$C$?4X?t$r%j%9%/4X?t$H$$$&!%695A$N0UL#$G$O!$%j%9%/4X?t$N:G>.2=$,E}7W3X$d3X=,M}O@$N%F!<%^$G$"$k!%?dDjNL$N4|BTCM$r(B $ E\hat{\theta}=\bar{\theta}$ $B$H$9$k$H(B,

MSE $\displaystyle =E[(\hat{\theta}-\bar{\theta}+\bar{\theta}-\theta
 )^{2}]$    
  $\displaystyle =E[(\hat{\theta}-\bar{\theta})^{2}+2(\hat{\theta}-\bar{\theta})(\bar
 {\theta}-\theta)+(\bar{\theta}-\theta)^{2}]$    
  $\displaystyle =E[(\hat{\theta}-\bar{\theta})^{2}]+(\bar{\theta}-\theta)^{2}
 %
$ (4.2)

$BBh0l9`(B $ E[(\hat{\theta}-\bar{\theta})^{2}]$ $B$O?dDjJ,;6!%BhFs9`$O%P%$%"%9$NFs>h$G$"$k!%=>$C$F%P%$%"%9$,$J$/!$J,;6$,>.$5$$?dDjNL$,K>$^$7$$?dDjNL$G$"$k!%(B $B3V$?$j$N$"$k?dDjNL$,>.$5$$J,;6$r;}$A!$$=$N(BMSE$B$,2DG=$JITJP?dDjNL$N(BMSE$B$h$j$b>.$5$/$J$k$3$H$O$"$j$&$k!%$3$l$,K>$^$7$$?dDjNL$G$"$k$N$O4V0c$$$J$$$,!$Nr;KE*$K$OITJP@-!$M-8z@-$OJL!9$K6cL#$5$l$F$-$?!%$^$:IaJW@-$N$"$k?dDjNL$r8+$D$1$F!$.$N$b$N$rA*$V$H$$$&

$BLdBj(B 18   Gauss$BJ,I[$K=>$&3NN(JQ?t$KBP$9$kE}7WNL(B $ S_{n-1},S_{n},S_{n+1}$ $B$N(BMSE$B$r5a$a$h!%(B

$B$?$@$7(B $ S_{n-1}^{2}=\frac{1}{n-1}\sum_{i=1}^{n}(X_{i}-\bar
{X})^{2}$ $B!$(B $ S_{n}^{2}=\frac{1}{n}\sum_{i=1}^{n}(X_{i}-\bar{X})^{2}$ , $ S_{n+1}^{2}=\frac{1}{n+1}\sum_{i=1}^{n}(X_{i}-\bar{X})^{2}$ .

$B$I$l$,0lHV>.$5$$$+!%(B

$B2rK!(B 19   MSE $ (S_{n+1})<$ MSE $ (S_{n})\leq$ MSE$ (S_{n-1})$

MSE$\displaystyle (S_{n-1})$ $\displaystyle =E(S_{n-1}-\sigma^{2})^{2}=\frac{2}{n-1}\sigma^{4}$    
MSE$\displaystyle (S_{n})$ $\displaystyle =E(S_{n}-\sigma^{2})^{2}=\frac{2n-1}{n^{2}}\sigma^{4}$    
MSE$\displaystyle (S_{n+1})$ $\displaystyle =E(S_{n+1}-\sigma^{2})^{2}=\frac{2}{n+1}\sigma^{2}%
$    


$B:GL`?dDj(B

$BL`EY(B(likelihood)$B$r:GBg$K$9$k%Q%i%a!<%?$r:GL`?dDjNL$H$$$&!%(B

$\displaystyle l(\theta)=\log p\left( X\vert\theta\right) =\sum\log p\left( X_{i}%
\vert\theta\right)
$

$BNc(B    $B%]%"%=%sJ,I[$N>l9g(B

$\displaystyle l(\theta)$ $\displaystyle =\sum_{i=1}^{n}\log p\left( X_{i}\vert\theta,\Delta\right)$    
  $\displaystyle =\sum_{i=1}^{n}\log\frac{\left( \theta\Delta\right) ^{X_{i}}}{X_{i}%
!}e^{-\theta\Delta}$    
  $\displaystyle =\sum_{i=1}^{n}[X_{i}\log\left( \theta\Delta\right) -\theta\Delta-\log
 X_{i}!]$    

$B:GL`?dDj$O(B

$\displaystyle \frac{\partial l(\theta)}{\partial\theta}$ $\displaystyle =\sum_{i=1}^{n}[\frac{X_{i}%
}{\theta}-\Delta]$    
  $\displaystyle =\frac{\sum_{i=1}^{n}X_{i}}{\theta}-n\Delta$    

$ \frac{\partial l(\theta)}{\partial\theta}=0$ $B$h$j(B

$\displaystyle \hat{\theta}_{n}=\frac{\sum_{i=1}^{n}X_{i}}{n\Delta}=\frac{\bar{X}}{\Delta}%
$

$B$?$@$7J?6QCM(B $ \bar{X}=\frac{1}{n}\sum
X_{i}$

$B:GL`?dDjCM$N4|BTCM$O(B

$\displaystyle E\hat{\theta}_{n}=\frac{\sum_{i=1}^{n}EX_{i}}{n\Delta}=\theta
$

$BJ,;6$O(B

$\displaystyle E(\hat{\theta}_{n}-E\hat{\theta}_{n})^{2}$ $\displaystyle =E\left[ \frac{\sum_{i=1}%
^{n}X_{i}}{n\Delta}-\theta\right] ^{2}$    
  $\displaystyle =\frac{1}{(n\Delta)^{2}}\sum_{i=1}^{n}E(X_{i}-\Delta\theta)^{2}$    
  $\displaystyle =\frac{\theta}{n\Delta}%
$    

$B:G8e$NEy<0$K$O%]%"%=%sJ,I[$N@- $ E(X_{i}-\Delta\theta)^{2}=EX_{i}=\Delta\theta$ $B$rMQ$$$?!%(B

$B==J,E}7WNL(B

$BH/2PN((B$ \lambda$ $B$NDj>o%]%"%=%s2aDx$K=>$&%9%Q%$%/;~7ONs$rF@$?$H$7$h$&!%%9%Q%$%/;~7ONs$r$4$/C;$$(B$ \Delta$ $BIC$N(B$ n$ $B8D$N%S%s$K6h@Z$j!$(B$ t$ $BHVL\$N%S%s$K%9%Q%$%/$,B8:_$9$l$P(B$ X_{t}=0$ $B!$$7$J$1$l$P(B$ X_{t}=1$ $B$H$7$F!$(B $ X=\left(
X_{1},X_{2},\ldots,X_{n}\right) $ $B$r%Y%k%L!<%$2aDx$H8+$J$9!%(B $B$3$N$H$-E}7WNL(B $ T=\sum_{t=1}^{n}X_{i}$ $B$O%Y%k%L!<%$2aDx$N(B$ \lambda$ $B$K4X$9$k==J,E}7WNL$G$"$k!%(B

$\displaystyle P\left( X\vert\lambda,\Delta\right)$ $\displaystyle =%
{\displaystyle\prod\limits_{t=1}^{n}}
 P\left( X_{i}\vert\lambda,\Delta\right)$    
  $\displaystyle =%
{\displaystyle\prod\limits_{t=1}^{n}}
 (\lambda\Delta)^{X_{i}}\left( 1-\lambda\Delta\right) ^{1-X_{i}}$    
  $\displaystyle =(\lambda\Delta)^{X_{1}+X_{2}+\cdots+X_{n}}(1-\lambda\Delta)^{n-(X_{1}%
+X_{2}+\cdots+X_{n})}%
$    

$ \Delta$ $B$O7h$^$C$F$$$k$H$9$l$P!$(B$ \lambda$ $B$NCM$r?dDj$9$k$N$K!$$3$3$N%G!<%?(B $ \left( X_{1},X_{2},\ldots,X_{n}\right)$ $B$OI,MW$G$J$/!$E}7WNL(B $ T=\sum_{t=1}^{n}X_{i}$ $B$rMQ$$$l$P==J,$G$"$k$3$H$,$o$+$k!%(B

$B:#EY$ODj>o%]%"%=%s2aDx$r$d$dBg$-$a$N(B$ n$ $B8D$N4QB,6h4V(B$ \Delta$ $B$G6h@Z$C$?$H$7$h$&!%(B $B$3$N$H$-3F6h4VFb$N%9%Q%$%/$N8D?t(B $ X=\left(
X_{1},X_{2},\ldots,X_{n}\right) $ $B$OJ?6Q(B $ \lambda \Delta$ $B$N%]%"%=%sJ,I[$K=>$&!%$3$N$H$-(B $ T=\sum_{t=1}^{n}X_{i}$ $B$O(B$ \lambda$ $B$K4X$9$k==J,E}7WNL$G$"$k!%(B

$\displaystyle P\left( X\vert\lambda,\Delta\right)$ $\displaystyle =%
{\displaystyle\prod\limits_{i=1}^{n}}
 P\left( X_{i}\vert\lambda,\Delta\right)$    
  $\displaystyle =%
{\displaystyle\prod\limits_{t=1}^{n}}
 \frac{\left( \lambda\Delta\right) ^{X_{i}}}{X_{i}!}e^{-\lambda\Delta}$    
  $\displaystyle =\frac{1}{X_{1}!X_{1}!\cdots X_{n}!}\cdot\left( \lambda\Delta\right)
 ^{X_{1}+X_{2}+\cdots+X_{n}}e^{-n\lambda\Delta}%
$    

$B:GL`?dDj$r9M$($F$_$h$&!%0x;R(B $ \frac{1}{X_{1}!X_{1}!\cdots X_{n}!}$ $B$O(B$ \lambda$ $B$K4X78$,$J$$!%(B $ \lambda$ $B$K4X78$9$kBhFs0x;R$O(B $ \left( \lambda\Delta\right) ^{T}e^{-n\lambda\Delta
}$ $B$H(B$ T$ $B$N4X?t$H$7$F=q$1$k$+$i!$8D!9$N%G!<%?$rCN$kI,MW$O$J$$$3$H$,$o$+$k!%(B

$B0lHL$KL)EYJ,I[$N%b%G%k(B $ f\left( x\vert\theta\right) $ $B$,(B

$\displaystyle f\left( x\vert\theta\right) =h\left( x\right) g\left( T\left( x\right)
 \vert\theta\right)$ (4.3)

$B$N7A$K0x;RJ,2r$G$-$k>l9g!$$+$D$=$N>l9g$K8B$j!$E}7WNL(B$ T$ $B$O%b%G%k%Q%i%a!<%?(B$ \theta$ $B$N==J,E}7WNL$G$"$k!%$3$l$r%U%#%C%7%c!$B!%L)EYJ,I[$N%b%G%k(B $ f\left( x\vert\theta\right) $ $B$r(B$ \theta$ $B$K0MB8$9$k0x;R$H0MB8$7$J$$0x;R$KJ,2r$G$-$F(B, $B0MB8$9$k0x;R$,E}7WNL(B $ T\left( x\right) $ $B$N4X?t$GI=$9$3$H$,$G$-$k$H$9$l$P!$(B$ \theta$ $B$N?dDj$K$O(B $ T\left( x\right) $ $B$rMQ$$$l$P==J,$G$"$k!%%Y%k%L!<%$2aDx$NNc$G$O(B $ h\left( x\right) =1$ $B!$(B $ g\left( T\left( x\right) \vert\theta\right)
=\theta^{T}(1-\theta)^{n-T}$ $B$H8+$F!$(B $ T=\sum_{t=1}^{n}X_{i}$ $B$,==J,E}7WNL$G$"$k$3$H$,$o$+$k!%$^$?%]%"%=%sJ,I[$O(B $ h\left(
x\right) =\frac{1}{X_{1}!X_{1}!\cdots X_{n}!}$ $B!$(B $ g\left( T\left( x\right)
\vert\theta\right) =\left( \lambda\Delta\right) ^{T}e^{-n\lambda\Delta}$ $B$H$J$j!$(B $ T=\sum_{t=1}^{n}X_{i}$ $B$,==J,E}7WNL$G$"$k$3$H$,$o$+$k!%(B

$BDj5A(B 20   $B%G!<%?(B $ X=\left(
X_{1},X_{2},\ldots,X_{n}\right) $ $B$,(B $ T\left( X\right) $ $B$,M?$($i$l$?2<$G(B$ \theta$ $B$HFHN)$J;~(B, $B4X?t(B $ T\left( X\right) $ $B$r%b%G%k(B $ f\left( x\vert\theta\right) $ $B$N==J,E}7WNL$H$$$&!%(B

$\displaystyle P\left( X=x\vert T\left( X\right) =t,\theta\right) =P\left( X=x\vert T\left(
X\right) =t\right)
$


$B%U%#%C%7%c!<>pJsNL(B

$B%9%3%"(B$B$H8F$P$l$kE}7WNL$rF3F~$9$k(B

$\displaystyle V\left( X;\theta\right) =\frac{\partial}{\partial\theta}\log f\le...
...ert\theta\right) }\frac{\partial f\left(
 X\vert\theta\right) }{\partial\theta}$ (4.4)

$B%9%3%"$N4|BTCM$O(B

$\displaystyle E[V]$ $\displaystyle =\int V\left( x;\theta\right) f\left( X\vert\theta\right) dx$    
  $\displaystyle =\int\frac{\partial f\left( x\vert\theta\right) }{\partial\theta}dx$    
  $\displaystyle =\frac{\partial}{\partial\theta}\int f\left( x\vert\theta\right) dx$    
  $\displaystyle =0$    

$B%9%3%"$NJ,;6$O(B

$\displaystyle E[V^{2}]=E\left[ \frac{\partial}{\partial\theta}\log f\left( X\vert\theta
\right) \right] ^{2}%
$

$B%9%3%"$NJ,;6$r%U%#%C%7%c!<>pJsNL(B$B$H$h$S!$(B $ J\left( \theta\right) =E[V^{2}]$ $B$GI=$9!%(B

$B3NN(JQ?t$K4X$9$k%3!<%7! )

$\displaystyle \vert E [X Y]\vert^2 \leq E X^2 E Y^2$ (4.5)

$B$rMQ$$$l$P

$\displaystyle E[V^{2}]\cdot E[(\hat{\theta}-\bar{\theta})^{2}]\geq\left\vert E\left[
V(\hat{\theta}-\bar{\theta})\right] \right\vert ^{2}
$

$B$3$3$G:8JU$NBh0l0x;R$O%U%#%C%7%c!<>pJsNL(B $ E[V^{2}]=J\left( \theta\right) $ $B!%(B $BBhFs0x;R$O?dDjNL$NJ,;6!$(B $ var\hat{\theta}=E[(\hat{\theta}-\bar{\theta})^{2}]$ $B$G$"$k!%1&JU$K$D$$$F$O$OFs>h$NCf?H$,(B

$\displaystyle EV\hat{\theta}$ $\displaystyle =%
{\displaystyle\int}
 V(\hat{\theta}-\bar{\theta})f\left( x\right) dx$    
  $\displaystyle =\int\frac{1}{f\left( x\vert\theta\right) }\frac{\partial f\left(...
...ht) }{\partial\theta}(\hat{\theta}-\bar{\theta})f\left(
 x\vert\theta\right) dx$    
  $\displaystyle =\int(\hat{\theta}-\bar{\theta})\frac{\partial f\left( x\vert\theta\right)
 }{\partial\theta}dx$    
  $\displaystyle =\int\hat{\theta}\frac{\partial f\left( x\vert\theta\right) }{\pa...
...\bar{\theta}\frac{\partial}{\partial\theta}\int f\left( x\vert\theta\right)
 dx$    
  $\displaystyle =\frac{\partial}{\partial\theta}\int\hat{\theta}f\left( x\vert\theta\right)
 dx$    
  $\displaystyle =\frac{\partial}{\partial\theta}E\hat{\theta}%
$    

$B$H$J$k!%$f$($KE}7WNL$NJ,;6$N2<8B$O%U%#%C%7%c!<>pJsNL$N5U?t$GM?$($i$l$k!%(B

$\displaystyle var\hat{\theta}\geq\frac{\left( \frac{\partial E\hat{\theta}}{\partial\theta
 }\right) ^{2}}{J\left( \theta\right) }%
$ (4.6)

$B$3$NITEy<0$r%/%i%^!$B$H$$$&!%%U%#%C%7%c!<>pJsNL$OE}7WNL$r$"$kFCDj$N%b%G%k(B $ f\left( x\vert\theta\right) $ $B$N%Q%i%a!<%?(B$ \theta$ $B$N?dDjCM$KMQ$$$k>l9g$NJ,;6$N2<8B$rM?$($k!%ITJP?dDjNL(B $ E\hat{\theta}=\theta$ $B$N>l9g(B

$\displaystyle var\hat{\theta}\geq\frac{1}{J\left( \theta\right) }%
$ (4.7)

$B%P%$%"%9$,$"$k>l9g$O(B $ E\hat{\theta}=\theta+b\left( \theta\right)
$

$\displaystyle var\hat{\theta}\geq\frac{1+b^{\prime}\left( \theta\right) }{J\left(
 \theta\right) }%
$ (4.8)

$B%U%#%C%7%c!<>pJsNL$O

$\displaystyle J\left( \theta\right) =E\left[ \left( \frac{\partial}{\partial\th...
...ac{\partial^{2}%
}{\partial\theta^{2}}\log f\left( x\vert\theta\right) \right]$ (4.9)

$BLdBj(B 21   $B3NN(JQ?t$K4X$9$k%3!<%7! )$B$rF3$-$J$5$$!%(B

$BLdBj(B 22   $B%U%#%C%7%c!<>pJsNL$NEy<0$r>ZL@$7$J$5$$!%(B

$B2rK!(B 23   $B1&JU$NCf?H$K$D$$$F(B

$\displaystyle -\frac{\partial^{2}}{\partial\theta^{2}}\log f\left( x;\theta\rig...
...me}}}{f^{2}}=-\frac{f^{^{\prime\prime}}}{f}+\frac{(f^{^{\prime}})^{2}}{f^{2}}
$

$B$N4X78$,$"$k$+$i!$4|BTCM$r$H$C$F(B

$\displaystyle E\left[ -\frac{f^{^{\prime\prime}}}{f}+\left( \frac{f^{^{\prime}}...
...}}{f}\right]
^{2}=E\left[ \frac{\partial}{\partial\theta}\log f\right] ^{2}%
$

$B%]%"%=%sJ,I[$N%U%#%C%7%c!<>pJsNL!%(B

$BDj>o%]%"%=%s%9%Q%$%/;~7ONs$r(B$ n$ $B8D$N4QB,6h4V(B$ \Delta$ $B$G6h@Z$C$?$H$7$h$&!%$3$N$H$-3F6h4VFb$N%9%Q%$%/$N8D?t(B $ X=\left(
X_{1},X_{2},\ldots,X_{n}\right) $ $B$OJ?6Q(B $ \lambda \Delta$ $B$N%]%"%=%sJ,I[(B

$\displaystyle \Pr\left( X=\left( X_{1},X_{2},\ldots,X_{n}\right) \vert\lambda,\...
...^{n}}
\frac{\left( \lambda\Delta\right) ^{X_{i}}}{X_{i}!}e^{-\lambda\Delta}%
$

$B$K=>$&!%%U%#%C%7%c!<>pJsNL$O(B

$\displaystyle J\left( \lambda\right)$ $\displaystyle =-E\left[ \frac{\partial^{2}}{\partial
 \lambda^{2}}\log f\left( X;\lambda,\Delta\right) \right]$    
  $\displaystyle =-E\left[ \frac{\partial^{2}}{\partial\lambda^{2}}\sum_{i=1}^{n}\left(
 X_{i}\log\lambda\Delta-\lambda\Delta-\log X_{i}!\right) \right]$    
  $\displaystyle =-E\left[ \sum_{i=1}^{n}\frac{\partial}{\partial\lambda}\left( X_{i}%
\frac{1}{\lambda}-\Delta\right) \right]$    
  $\displaystyle =\frac{\sum_{i=1}^{n}EX_{i}}{\lambda^{2}}$    
  $\displaystyle =\frac{n\lambda\Delta}{\lambda^{2}}=\frac{n\Delta}{\lambda}%
$    

$B=>$C$FJ,;6$N2<8B$O(B $ \lambda/n\Delta$ $B!%(B

$BLdBj(B 24   $B%]%"%=%sJ,I[$N(B$ \lambda$ $B$K4X$9$k%U%#%C%7%c!<>pJsNL$r8x<0(B $ J\left( \theta\right) =E\left[ \left( \frac{\partial
}{\partial\theta}\log f\left( x\vert\theta\right) \right) ^{2}\right]$ $B$rMQ$$$FF3=P$;$h!%(B

$BLdBj(B 25  


$B;X?tJ,I[$N%U%#%C%7%c!<>pJsNL$r5a$a$h!%(B

$B2rK!(B 26   $BJ?6Q(B$ 1/\lambda$ $B$N;X?tJ,I[(B $ f\left(
x;\lambda\right) =\lambda e^{-\lambda x}$ $B$N(B$ \lambda$ $B$K4X$9$k%U%#%C%7%c!<>pJsNL$O(B

$\displaystyle J\left( \lambda\right) =-E\left[ \frac{\partial^{2}}{\partial\lam...
...al\lambda}\left( \frac{1}{\lambda}-x\right) \right] =\frac
{1}{\lambda^{2}}%
$

$B$f$($KJ,;6$N2<8B$O(B $ \lambda^{2}$ $B!%(B

$B%Y%$%:?dDj!J$O$d$o$+$j!K(B

Bayes$B$NDjM}(B

$\displaystyle p\left( \theta\vert x,w\right) =\frac{p(x\vert\theta)\pi(\theta\vert w)}{p(x\vert w)}%
$

$ p(x\vert\theta)$ $B$rL`EY(B(likelihood)$B!$(B $ \pi(\theta)$ $B$r;vA0J,I[(B(prior distribution)$B!$(B $ p\left( \theta\vert x\right) $ $B$r;v8eJ,I[(B(posterior distribution)$B$H$$$&!%(B

$BJ,Jl$O@55,2=9`$GJ,;R$NAmOB$r$H$C$F(B

$\displaystyle p(x\vert w)=\int p\left( x,\theta\vert w\right) d\theta
$

$B$GM?$($i$l$k!%<~JUL`EY4X?t!&%(%S%G%s%9$H$$$&!%(B

$B;v8eJ,I[$K$h$k?dDjCM(B

$B;v8eB;<:4X?t(B(posterior loss function, posterior expected loss) $B$rDj5A$7!$;v8eJ,I[$K$h$k4|BTCM(B: $B;v8e%j%9%/4X?t(B(posterior risk function)    

$\displaystyle L^{\text{Bayes}}(\delta,\theta;X,w)\equiv E^{\theta\vert X,w}[L(\...
...a)]=\int L\left( \delta,\theta\right) p\left( \theta\vert X,w\right)
d\theta
$

$B$r:G>.2=$9$k%Q%i%a!<%?$r?dDjNL$H$9$k(B

$\displaystyle \hat{\theta}_{\text{Bayes}}(X,w)=\arg\underset{\theta}{\min}L^{\text{Bayes}%
}(\delta,\theta;X,w)
$

$BB;<:4X?t$H$7$F;Y;}4X?t(B(indicator function)$ L_{0}$

$\displaystyle L_{0}(\delta,\theta)=1_{\delta,\theta}
$

$B$rA*$V$H(BMAP$B?dDjCM(B(maximum a posteriori estimate)$B$,F@$i$l$k!%(B

$\displaystyle \hat{\theta}_{\text{MAP}}(X,w)=\arg\underset{\theta}{\max}p\left(
\theta\vert X,w\right)
$

$BB;<:4X?t$H$7$F@dBP8m:9(B$ L_{1}$

$\displaystyle L_{1}(\delta,\theta)=\vert\delta-\theta\vert
$

$B$rA*$V$H;v8eCf1{CM?dDj(B(posterior median)$B$,F@$i$l$k!%(B

$BB;<:4X?t$H$7$FFs>h8m:9(B$ L_{2}$

$\displaystyle L_{2}(\delta,\theta)=(\delta-\theta)^{2}%
$

$B$rMQ$$$k$H;v8eJ?6Q(B(posterior mean)

$\displaystyle \hat{\theta}_{\text{PM}}(X,w)=\int\theta p\left( \theta\vert X,w\right) d\theta
$

$B$,F@$i$l$k!%;v8eJ?6Q$rFC$K%Y%$%:?dDjCM(B(Bayes estimate)$B$H8F$V$3$H$,$"$k!%(B

$BLdBj(B 27   $B;v8eB;<:(B $ L^{Post}(\delta,\theta)$ $B:G>.2=$N86M}$+$i(BMAP$B?dDjCM!$;v8eJ?6QCM$r5a$a$h!%(B

$B7P83%Y%$%:?dDjNL(B

$B%Y%$%:?dDjNL$OD6%Q%i%a!<%?$K0MB8$9$k!%D6%Q%i%a!<%?$r:GL`?dDj$G5a$a%Y%$%:?dDjNL$KMQ$$$k$3$H$r7P83%Y%$%:K!$H8F$V(B(empirical Bayes estimator)$B!%(B

$B<~JUL`EY(B

$\displaystyle p(x\vert w)=\int p\left( x,\theta\vert w\right) d\theta=\int p(x\vert\theta)\pi
(\theta\vert w)d\theta
$

$B<~JUL`EY$N:GL`?dDjCM(B($B<~JUL`EY:GBg2=(B)

$\displaystyle \hat{w}=\arg\underset{w}{\max}p(x\vert w)
$

$B7P83%Y%$%:?dDjNL$O:GE,2=$7$?D6%Q%i%a!<%?(B$ \hat{w}$ $B$rMQ$$$F(B

$\displaystyle \hat{\theta}_{\text{EB}}(X)=\hat{\theta}_{\text{Bayes}}(X,\hat{w})
$

$B$GM?$($i$l$k!%(B



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