Reference no: EM132337920

1. What is the causal hypothesis at issue?

2. What kind of causal experiment is undertaken?

3. What crucial facts and figures are missing from the report?

Researchers have shown for the first time that nonsmoking adults who grew up in households with smokers have an increased risk of lung cancer. Although 83% of all lung cancer occurs among cigarette smokers, the researchers said their findings suggested that 17% of the cases among nonsmokers result from secondhand tobacco smoke they breathed at home as children. The report was written by Dr. Dwight T. Janerich. Janerich's team studied 191 patients who had been diagnosed with lung cancer between 1982 and 1984. The patients had either never smoked more than 100 cigarettes or had smoked at one time but not more than 100 cigarettes in the 10 years before the diagnosis of cancer. The group was compared with an equal number of people without lung cancer who had never smoked. The researchers added up the number of years each person lived in a house and multiplied it by the number of smokers to calculate smoker years. The researchers found that household exposure to smokers for 25 or more years during childhood and adolescence doubled the risk of lung cancer. The risk of lung cancer did not appear to increase with household exposure during adult life.