A researcher wishes to understand if there is a relationship between room lighting and quality of work. To do this, he gathers 300 people and places them in three separate rooms (one with dim light, one with normal light, and one with bright light). They are given one hour to proofread an essay, and afterwards, their completion and accuracy is recorded. Is this an observational study or an experiment? Why? Identify the sample and population of this study. Describe how matching, based on previous work, can be used to create these groups. Identify the control and treatment groups. The subjects did not know what the purpose ofthe study was, and the researcher did not know who was assigned to which group until after data was collected. What feature does this lack of knowledge describe