Cell phone risks

Researchers at the Washington University School of Medicine randomly placed 480 rats into one of three chambers containing radio antennas. One group was exposed to digital cell phone radio waves, the second to analog cell phone waves, and the third group to no radio waves. Two years later the rats were examined for signs of brain tumors. In June 2002 the scientists said that differences among the three groups were not statistically significant.

a) Is this a study or an experiment? Explain.

b) Explain in this context what statistically significant means.

c) Comment on the fact that this research was supported by funding from Motorola, a manufacturer of cell phones.