Fix the mistake: Sample Surveys
Statistical Surveys ① Census and Sample Surveys
There are two ways to collect data.
- Census: Investigating everyone in the population (examples: population census, health examinations)
- Sample survey: Investigating a sample taken from the population (examples: opinion polls on cabinet approval ratings, food quality inspections)
📘 Example ①
Which of the following is suitable for a sample survey?
(A) Measuring the height of every student in a school
(B) Estimating the number of fish in a pond
Answer:(B) A sample survey is suitable because it is difficult to catch all the fish. (A) is a census.
Which of the following is suitable for a sample survey?
(A) Measuring the height of every student in a school
(B) Estimating the number of fish in a pond
Answer:(B) A sample survey is suitable because it is difficult to catch all the fish. (A) is a census.
💡 Key Point
- Census: Investigates everyone (accurate but requires time and money)
- Sample survey: Investigates part of the population to estimate the whole (efficient but has error)
- Destructive tests (such as testing the life of light bulbs) must use sample surveys
Practice Problem
- For testing the life of light bulbs, which is more suitable, a census or a sample survey? Answer with a reason.
Answer and Explanation
- Answer:A sample survey. If a census were conducted, all the light bulbs would be used up, so they could not be sold as products.
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