Experimental or observational?
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Identify each study as either experimental or observational
1. A sample of fish taken from a river to measure the level of mercury in the fish
2. A research scientist gives a weight loss drug to a group of 500 patients and a placebo to another 500 patients to determine if the weight loss drug has an effect on the patients.
1st one is observation because of too many uncontrolled factors that enter the test results. The latter is an experiment for it can be controlled.
The first study is observational, because you’re just taking fish, you’re not manipulating them in any way. The second study is experimental; there are two populations, one of which is acting as a control, as well as dependent and independent variables.