Professor Oak runs a study to examine whether water-type Pok…

Professor Oak runs a study to examine whether water-type Pokemon are more naturally buoyant than other types of Pokemon. To test this, he gathers a sample of 100 different Pokemon, placing the Pokemon into two groups: water-types and non-water-types. He tests both groups in their swimming and floating capabilities, and then uses statistics to compare performance between the two groups. What kind of study is this?