Theorem
Stein's Lemma and Metrics via Stein's Eq
Stein's Lemma
Stein's Equation
Let $\mathcal{H}$ be a seperating class and let $h \in \mathcal{H}$.
Let $f_h$ be the solution to the Stein Equation associated with $h$. Then
\[
f'_h(x)-xf_h(x) = h(x)-\mathbb{E}(h(N))
\]
Let $F$ be a real valued random variable, then
\[
f'_h(F)-Ff_h(F) = h(F)-\mathbb{E}(h(N))
\]
Taking expectations on both sides
\[
\mathbb{E}(h(F))-\mathbb{E}(h(N)) = \mathbb{E}(f'_h(F)-Ff_h(F))
\]
Taking absolute values
\[
| \mathbb{E}(h(F))-\mathbb{E}(h(N))| = |\mathbb{E}(f'_h(F)-Ff_h(F))|
\]
Taking a $\sup$ over $\mathcal{H}$,
\[
d_{\mathcal{H}}(F,N)= \sup_{h \in \mathcal{H}} | \mathbb{E}(h(F))-\mathbb{E}(h(N))| = \sup_{h \in \mathcal{H}} |\mathbb{E}(f'_h(F)-Ff_h(F))|
\]
Metric on the Space of Probability Measures
Dependency Graph
flowchart LR
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n52ca04cc["Stein's Lemma"]
n19bfbd84["Stein's Equation"]
nf64c7c47["Metric on the Space of Probability Measures"]
nac623bd2["Stein's Lemma and Metrics via Stein's Eq"]:::current
n52ca04cc --> nac623bd2
n19bfbd84 --> nac623bd2
nf64c7c47 --> nac623bd2
click n52ca04cc "../objects/52ca04cc.html" "_self"
click n19bfbd84 "../objects/19bfbd84.html" "_self"
click nf64c7c47 "../objects/f64c7c47.html" "_self"