= Poisson likelihood-ratio CUSUM
{c}
{title2=$W_t=Y_t\log\theta-(\theta-1)\lambda_{0t}$}
For independent <Poisson> observations, comparing mean $\lambda_{0t}$ with $\theta\lambda_{0t}$ gives the displayed <log-likelihood ratio>. Updating a <CUSUM> with these scores targets the specified multiplicative increase. Its expected score is negative under the null and positive under the alternative when $\theta>1$, so resetting at zero discards earlier evidence against an increase.
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