Anew drug is being tested on mice. one dozen mice are given the new drug and tested, while another dozen mice are not given anything and tested. what kind of data collection is this?

There are many types of data collection. These types are generally classified as quantitative or qualitative data collection. Under the quantitative data collection are Census, sample survey, administrative data, and sample studies. On the other hand, under the qualitative data collection are questionnaire type, interviews, focus groups, observation, and case study. 

As far as this scenario is concerned, the type of data collection used is a qualitative one since it does not matter how many the samples are. Rather, what matters are the quality or behaviour of the samples. To be specific, this is a qualitative observation data collection.