Biased vs. Unbiased Sampling

Match the terms to be sure you have them straight in your mind! Biased Sample Not fair; Favors one outcome Unbiased Sample Fair; Represents population Match these two surveys as biased or unbiased. Unbiased Survey Surveying students about their favorite color but choosing names randomly from a hat Biased Survey Surveying the first 10 boys to arrive at school about their favorite color Jack wants to sample students to find out how many books they read over the summer. Which of the following groups would be a random and unbiased sample? All students in the library All the students in an honors math class Every tenth student to enter the lunch room Watch this video to learn more about random and unbiased sampling. Be ready to answer more questions! Which sample is random and unbiased? Leslie wants to determine eating habits of people in her neighborhood. She asks 80 people at a neighborhood fast food restaurant about their favorite place to eat. Liz wants to find out the favorite sport of girls in her school. She asks all girls on the school basketball team what their favorite sport is. Susan wants to know the favorite movie of students in her class. She gives the students a number and puts all numbers in a hat. She draws 10 numbers and surveys those students. Which survey is biased and not fair? To evaluate the quality of their product, a manufacturer of cell phones checks every 50th phone off the assembly line. To find how much money the average American family spends to cool their home, 100 Alaskan families are surveyed at random. Manny wants to determine the amount of time 7th graders spend studying for the math exam, so he surveys 80 random 7th grade students. Sort the surveys into categories: Biased and Unbiased. Biased (Not Fair) Surveying only your friends about their favorite school subject Surveying the first 5 students that walk into the school about their favorite color Unbiased (Fair) Surveying every 5th student that walks into the cafeteria about their favorite color Randomly selecting one student from each homeroom about their favorite school subject Complete the blanks based on the scenario. William is surveying people at a shopping center to determine the most popular TV show. He wants his survey to be fair and unbiased, so he randomly selects every 5th person that walks into the entrance.