Recent research suggests that depression significantly increases the risk of developing dementia later in life (BBC News, July 6, 2010). In a study involving 949 elderly persons, it was reported that 22% of those who had depression went on to develop dementia, compared to only 17% of those who did not have depression.
a. Describe the relevant population and the sample.
b. Do the numbers 22% and 17% represent the population parameters or the sample statistics?