UNBIASED SAMPLE

Unbiased Sample

Definition Of Unbiased Sample

A sample is an unbiased sample if every individual or the element in the population has an equal chance of being selected.

Examples of Unbiased Sample

Kathy wants to know how many students in her city use the internet for learning purposes. She used an email poll. Based on the replies to her poll, she found that 83% of those surveyed used the internet. Kathy's sample is biased as she surveyed only the students those who use the internet. She should have randomly selected a few schools and colleges in the city to conduct the survey.

Video Examples: Unbiased Samples

Solved Example on Unbiased Sample

Ques: Which one of the following sampling methods would give unbiased results, if you need to find out the number of people in your town liking vanilla or chocolate ice creams?

Choices:

A. ask my neighbors
B. randomly select a few ice cream shops in town, and question people coming there
C. ask my friends
D. ask my classmates
Correct Answer: B

Solution:

Step 1: A sample is an unbiased sample if every individual or the element in the population has an equal chance of being selected
Step 2: Among the choices listed, randomly selecting a few ice cream shops in town, and questioning people coming there would be a good sampling method as people of different age groups have a chance of being surveyed. It could be a representative of the entire population in the town
Step 3: So, choice B is the correct answer.

Quick Summary

Every individual has an equal chance of selection.
Reduces selection bias.
Important for accurate data representation.

\[ P(selection) = 1/N, where N is the population size \]

🍎 Teacher Insights

Emphasize the importance of randomness and discuss real-world examples where biased samples lead to incorrect conclusions. Use simulations to demonstrate the difference between biased and unbiased sampling.

🎓 Prerequisites

Basic understanding of populations and samples
Concept of randomness

Check Your Knowledge

Q1: Which of the following sampling methods is most likely to produce an unbiased sample when surveying student opinions on school lunch?

A. Surveying all students in the cafeteria during lunch. B. Surveying members of the student council. C. Randomly selecting students from a school-wide list and surveying them. D. Surveying students in the cooking club.

Frequently Asked Questions

Q: Why is an unbiased sample important?
A: It ensures that the sample is representative of the population, leading to more accurate and reliable conclusions.

Q: How can I ensure my sample is unbiased?
A: Use random sampling techniques, such as simple random sampling, stratified sampling, or cluster sampling.