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A study investigated whether there was a higher risk of complications for a type

ID: 3218994 • Letter: A

Question

A study investigated whether there was a higher risk of complications for a type of colorectal surgery performed at a large urban hospital, University Hospital, versus a smaller regional hospital, County Hospital. 400 patients who had the surgery at County Hospital and 2,000 patients who had the surgery at University Hospital were studied. The following table summarizes the number of 'complications' in each group: a) Find the rate of complications in each group. Show your work below. County Hospital 3% University Hospital 8% b) Is this is an observational or an experimental study? Why?

Explanation / Answer

a) rate of complication in County Hospitals = 12/400 *100 % = 3 %

similary in University hostels = 160/2000 *100% = 8 %

b)In an experiment investigators apply treatments to experimental units (people, animals, plots of land, etc.) and then proceed to observe the effect of the treatments on the experimental units

whereas

In an observational study investigators observe subjects and measure variables of interest without assigning treatments to the subjects. The treatment that each subject receives is determined beyond the control of the investigator.

This is observational study . as no treatment was given, all surgery was done without control of investigators.