The EPA has clear data collection protocols for evaluating the safety of drinking water. To assess whether and how deviations from that protocol may affect data, the EPA selected a random sample of 32 homes in Chicago and collected water vials to determine water lead levels (in mcg/l). Chicago was used for the study because it is an old city with lead water pipes. For each house, a vial of tap water was collected first thing in the morning on two different random spring days. On one day, people were told to use the house as normal; on the other day, they were instructed to flush all house tabs for five minutes the night before. Lead levels were significantly higher*, on average, with normal use than with pre-flushing. ("statistical inference) 1. Who or what are the individuals/units in this study? homes in Chicago 2. What type of study is this? a case-control observational V