Is that you in the little video above? It’s me, just about every time. Why is it that no matter what line I get in, it’s always the one that ends up taking the most time to get out of?

Seems like if there are three lines open and I pick the one that looks the shortest, has the most competent shoppers in it, doesn’t look lie there are any “couponers” in it, etc., there will always be a problem. The other lines will move faster and if I switch, the one I was originally in will suddenly start moving and now I’m at the back of another line.

There is some math to this, although without the correct observational data it may not help you choose the best line.

Read the article in the link. And here are a couple of quick things to remember:

First off, realize this: If there are three lines to choose from, you only have a 1 in 3 chance to choose the fastest line right off the bat.

It might really make sense to switch to a different line (you could have a 2 in 3 chance of being better off after switching). See this description of the Monty Hall Problem.

Here’s one more link that gives an inordinate amount of attention to this problem, and also introduces the real root of the problem: The Inspection Paradox.