Single-crossing condition

Imagine you are at a playground and you want to go down the slide. The slide is one-way and goes down only, so you can't climb up it. You notice that there is a line of kids waiting to go down the slide, and they are standing in a single-file line. This is called a single-crossing condition.

In more grown-up terms, a single-crossing condition is a situation where there is only one dimension of comparison, and the values being compared are ordered along that dimension. This means that if you were to plot the values on a line, they would not cross each other.

For example, imagine you are ranking the popularity of different ice cream flavors. You might ask people to rate their favorite flavors from 1 to 10, with 1 being the most popular. If you plot these ratings on a graph, the ratings would form a straight line with no intersections or crossings.

Single-crossing conditions are important in many areas of study, including economics and political science, because they help us understand how people make decisions and how different factors influence those decisions.