Decide if the following scenario is an observational study, experiment or meta-analysis
Among a group of women aged 18 and older who were tracked for several years, those who exercised were less likely to suffer from depression as those who did not.
A sample of children were separated into two groups. One group was given a new toothpaste to use while the other group used their normal toothpaste. It was found that both groups of children averaged the same amount of cavities over a period of 2 years.
An examination of the medical records of more than 360,000 Swedish men showed that those who were overweight or who had high blood pressure had a higher risk of kidney cancer.
Recently, there was some concern about the safety of the “Big Dig”. Many studies of this issue have been done by several groups. The studies were put together, the data averaged and a new report issued.
Some people who race greyhounds give the dogs large doses of Vitamin C in the belief that the dogs will run faster. Investigators at the University of Florida tried three different diets in random order on each of the five racing greyhounds. They were surprised to find that when the dogs ate high amounts of Vitamin C they ran slower.