Sample Methods and Bias

A ___ is a large group that includes everything being studied.

• Sample

• Stratified Sampling Method

• Population

• Census

Identify the type of sampling used:

Interview every 10th student who enters the school in the morning.

• simple random sample

• voluntary response sample

• systematic sample

• convenience sample

Identify the type of sampling used:

Assign each car in a dealership a number and then use a random-number table to select the cars to be inspected.

• systematic sample

• simple random sample

• convenience sample

• voluntary response sample

Identify the type of sampling used:

Marianne wanted to know students' opinion on the new schedule at school. She survey's the first 30 students who come into her class.

• Convenience Sampling

• Systematic Random Sampling

• Simple Random Sampling

• Volunteer response

Disneyland often surveys its guests as they exit a restaurant during their visit. The surveyor stands at the restaurant exit, counts the number of people leaving, and surveys every 25th guest.
This is a form of:

• Simple Random Sample
• Stratified Random Sample
• Voluntary Response
• Systematic Random Sampling

An independent research company wants to go door to door to survey people in the city of West Palm Beach. The company decides to number all blocks within the city limits, randomly choose 1 block, and then survey all households on that block.

This is an example of:

• Simple Random Sample

• Stratified Random Sample

• Cluster Random Sample

• Systematic Random Sampling

A teacher hands out an index card and asks ALL of her students to write down the their age, height (in inches), and what grade they are in.

Which of the following best describes her method of data collection?

• Census

• Simple Random Sample

• Cluster Random Sample

• Stratified Random Sample

Identify the type of sampling used:

A teacher splits her classes up by period. She then uses an RNG (Random Number Generator) to select 10 students from each period to participate in a survey.

• Stratified Random Sample

• Systematic Random Sample

• Cluster Random Sample

• Biased Sample

Why do we randomly select our samples?

• for control
• reduce bias
• so we don't get the same answers from everyone
• to eliminate confounding results

Source of bias in which people CHOOSE to respond and usually only people with very strong opinions respond

• Response Bias
• Undercoverage
• Convenience Sampling
• Voluntary Response