In line at Safeway today I had a thought, what determine the probability that someone will switch lines?

I figure it has to rely on a decaying exponential that depends on time. These would increase the probability of switching lines:

- Number of people in front
- Length of other lines (if shorter)
- Speed at which current line is moving
- Size of cart/basket (if smaller)

While these factors would decrease the probability:

- Number of people behind
- Length of other lines if they are longer
- Speed of other lines
- Mobility of purchase load (if larger)
- Time invested in current line
- Loud or annoying people in other line

I am sure it is feasible to do a study on how often people do switch lines, likely similar to changing lanes in traffic. If that study exists or will one day exist I hope that a mathematical model is included. The major component will be e^(-α t) with α dependent on the person in line.