Errors occur in statistical sampling. We will understand methods for improving accuracy and points to note.
How to Reduce Errors
- Increase the sample size (take more samples)
- Conduct random sampling thoroughly (eliminate bias)
Points to Note in Statistical Sampling
- An estimate is an approximate value and may not match exactly
- If the sample is biased, the estimate will be inaccurate
📘 Example ① (Summary)
Marks were placed on and then returned to 200 fish in a pond. Later, when 60 fish were caught, 6 had marks. Estimate the total number of fish in the pond.
Answer: Proportion of marked fish = 6/60 = 1/10. Total number = 200 ÷ (1/10) = 2000 fish
Marks were placed on and then returned to 200 fish in a pond. Later, when 60 fish were caught, 6 had marks. Estimate the total number of fish in the pond.
Answer: Proportion of marked fish = 6/60 = 1/10. Total number = 200 ÷ (1/10) = 2000 fish
💡 Key Point
- Summary of statistical sampling: ① Decide whether to survey the entire population or a sample ② Use random sampling ③ Estimate using proportions or averages ④ Be careful about errors
Practice Problems
- State two important things for improving the accuracy of statistical sampling.
Answers and Explanations
- Answer: ① Increase the sample size ② Conduct random sampling (eliminate bias).