Herman Boncor, the local dogcatcher, thinks that the dogs at the pound tend to bark less when they are fed expensive brand-name dog food than when they are fed a cheaper generic brand of dog food. To test this hypothesis, he randomly selects 50 dogs from the pound. He feeds 25 of them the expensive brand-name dog food and the other 25 the cheaper generic brand of dog food. After observing the dogs for a week, he records the number of times each dog barks. What type of study is Herman conducting?
1) Observational study
2) Experimental study
3) Correlational study
4) Survey study