Final answer:
A population contains all members of a specified group, while a sample is a part of that population. The number of garages for each house on a street would be a population if all houses are considered, but a sample if only some houses are considered for inference about the whole street.
Step-by-step explanation:
The distinction between a population and a sample is crucial in statistics. A population is the entire group that you want information about, whereas a sample is a subset of that population. In the scenario where the number of garages for each house on a street is being considered, if we are looking at all the houses on that particular street, that would constitute a population because it is the entire group we're interested in. However, if we're only considering a portion of the houses on the street to make inferences about the whole street, then that would be a sample.
Examples of Population and Sample
Referring to the examples provided, the study done in San Jose on the age, number of times per week, and the duration of residents using a local park, is based on a sample since not all residents were interviewed, but rather every eighth house around the park was selected. This is an example of systematic sampling.
Another example is the insurance company which wishes to determine the proportion of all medical doctors involved in malpractice lawsuits. The population here would be all medical doctors, but the company only selected 500 doctors at random to gather information, making this group a sample.