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  • stepan-a/ispra-2024
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*.pdf
tex/auto
tex/slides.vrb
model/+fs2000/
model/fs2000/
......
......@@ -18,6 +18,7 @@ function densities = plot_all_distributions(modelname, nparticles, idparam)
plot3(densities{1,1}, ones(512,1), densities{1,2}, '-k')
hold on
for i=2:25, plot3(densities{i,1}, i*ones(512,1), densities{i,2}, '-k'), end
view(axes1,[-31.1204379546341 14.8026428177991]);
axis tight
grid on
hold off
......
File added
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......@@ -39,6 +39,7 @@
\addbibresource{slides.bib}
\usepackage{verbatimbox}
\usepackage{pgfplots}
\newcommand{\trace}{\mathrm{tr}}
\newcommand{\vect}{\mathrm{vec}}
......@@ -125,7 +126,7 @@
\medskip
\item If we obtain $\{x_i\}_{i=1}^N$ from another distribution $q(x)$:
\item If we obtain $\{x_i\}_{i=1}^N$ from another distribution with density $q(x)$:
\[
\mathbb E_p\left[ \varphi(X) \right] = \int q(x)\frac{p(x)}{q(x)}\varphi(x)\mathrm d x = \int q(x)\tilde{\omega}(x)\varphi(x)\mathrm d x = \mathbb E_q\left[ \tilde{\omega}(X)\varphi(X) \right]
\]
......@@ -147,7 +148,7 @@
\begin{itemize}
\item IS works as long as the support of the targetted distribution ($p$) is included in the support of the instrumental distribution ($q$).\newline
\item IS works as long as the support of the targeted distribution ($p$) is included in the support of the instrumental distribution ($q$).\newline
\item How do we choose distribution $q(x)$?\newline
......@@ -161,7 +162,7 @@
% ⇒ We are better off if the unormalized weight variance is low, i.e. if f/g is approximately constant.
% The closer g is to f, the better we are.
\item Is it possible to find a reasonable intrumental distribution for a posterior distribution?\newline
\item Is it possible to find a reasonable intrumental distribution for a posterior distribution? The prior?\newline
\item Probably better not to ``jump'' directly to the posterior distribution...
......@@ -184,14 +185,14 @@
\item[Target] $p\left(\theta|\mathcal Y_T\right) \propto p(\theta) p(\mathcal Y_T| \theta)$\newline
\item Consider the ''simplified`` object $p\left(\theta\right)p\left(\mathcal Y_T\right)^{\phi}$\newline
\item Consider the ''simplified`` object $p\left(\theta\right)p\left(\mathcal Y_T| \theta\right)^{\phi}$\newline
\item $p\left(\theta\right)$ is a good instrumental distribution for $p\left(\theta\right)p\left(\mathcal Y_T\right)^{\phi}$ for small values of $\phi$.\newline
\item $p\left(\theta\right)$ is a good instrumental distribution for $p\left(\theta\right)p\left(\mathcal Y_T| \theta\right)^{\phi}$ for small values of $\phi$.\newline
\item Consider a sequence of $\{\phi_i\}_{i=1}^M$ with $\phi_i<\phi_j$ for all $j>i$ and $\phi_M = 1$.\newline
\item Use $p\left(\theta\right)$ as an intrumental distribution for $p\left(\theta\right)p\left(\mathcal Y_T\right)^{\phi_1}$ and $p\left(\theta\right)p\left(\mathcal Y_T\right)^{\phi_i}$
as an instrumental distribution for $p\left(\theta\right)p\left(\mathcal Y_T\right)^{\phi_{i+1}}$.\newline
\item Use $p\left(\theta\right)$ as an intrumental distribution for $p\left(\theta\right)p\left(\mathcal Y_T| \theta\right)^{\phi_1}$ and $p\left(\theta\right)p\left(\mathcal Y_T| \theta\right)^{\phi_i}$
as an instrumental distribution for $p\left(\theta\right)p\left(\mathcal Y_T| \theta\right)^{\phi_{i+1}}$.\newline
\item Herbst and Schofheide consider $\phi_n = \left( \frac{n}{M} \right)^\lambda$ with $\lambda>1$ (convexity).
......@@ -292,13 +293,25 @@ posterior_sampling_options = ('particles', 20000,
\begin{frame}
\frametitle{Sequential importance sampling, V}
\begin{center}
\resizebox{\textwidth}{!}{\input{../model/distributions.tex}}
\end{center}
\end{frame}
\begin{frame}
\frametitle{Sequential importance sampling, VI}
\framesubtitle{TODO}
\begin{itemize}
\item More options.\newline
\item More options (number of mutation MH steps, resampling algorithm, ...).\newline
\item Complete posterior computations.\newline
\item Complete posterior computations (bayesian IRFs, forectasts, ...).\newline
\item No reason to start from the prior distribution.\newline
......