Say I have a List A of $1,000,000$ values, and List $B$ of $2,000,000$ values. I want to know what percent of List $B$ is in list A without looking at all $2,000,000$ values and referencing List $A$.
So, I want to only look at some of list $A$ and list $B$, rather than going through the entire list. Is there a way to reliably look at a percentage of the values of list $A$ and a percentage of the values of list $B$ (at random), compare those samples, and estimate the percent overlap for the entire lists $A$ and $B$?