Answer:
The description corresponds to an observational study.
Explanation:
In Observational studies, researchers observe the effect of a risk factor without changing what is exposed to it or its conditions. On the other hand, in an experimental study, researchers can introduce a change and study the effects of it.
I believe they attend meetings, vote to enact U.S laws, they express beliefs and provide input in debates . Centrally they are a important part of the legislative branch.
Answer: Selection bias
Explanation:
Selection bias is defined as the process in which individual or group of individual are analyzed for selection process by lacking randomization property .This process displays that selected sample of individuals is not similar representative of major interest population.
According to the question,the systematic difference that occurs in selected group for experiment as per their last name is displaying that selected group does not represent interest population that is causing systematic error.Thus, this situation describes about selection biasing.