Here is a short essay about an investigation.
There are also four questions/tasks; write a paragraph to answer each one of them.
1. Identify the causal hypothesis at issue.
2. Identify what kind of investigation it is.
3. There are control and experimental groups. State the difference in effect (or cause) between the control and experimental groups.
4. State the conclusion that you think is warranted by the report.
Scientists have learned that people who drink wine weekly or monthly are less likely to develop dementia, including Alzheimer's disease. (Daily wine drinking, however, seems to produce no protective effect.) The lead researcher was Dr. Thomas Truelsen of the Institute of Preventive Medicine at Kommunehospitalet in Copenhagen. The researchers identified the drinking patters of 1,709 people in Copenhagen in the 1970s and then assessed them for dementia in the 1990s, when they were aged 65 or older. When they were assessed two decades later, 83 of the participants had developed dementia. People who drank beer regularly were an increased risk of developing dementia.
-adapted from BBC News Online.