Sampling and Bias Review

A set of observations that constitute PART of the population.

• Statistic

• Census

• Population

• Sample

Sampling method that consists of n individuals from the population chosen in such a way that every individual has an EQUAL chance of being selected.

• Stratified Sampling

• Simple Random Sampling (SRS)

• Cluster Sampling

• Systematic Sampling

I want to estimate the proportion of all adults in Chula Vista who graduated from high school. I select a random sample of addresses and go to those houses. When an adult answers the door, I ask if they had graduated from high school. If a child answers the door, I ask for an adult. If there is none there at the time, I return at another time to complete the survey. What is the most prominent bias?

• Non-response bias

• Response bias

• Voluntary response bias

• Undercoverage

I want to estimate the proportion of people in Chula Vista who own cats. I stand outside a local pet store and ask every 4th person whether they own a cat or not. What is the most prominent kind of bias evident?

• Undercoverage

• Response

• Non-Response

• Voluntary Response

In order to estimate the proportion of students that text while driving, a school administrator selects a simple random sample of students from a list of all students at the school who have parking permits. The students are called to the office, one at a time. The administrator asks each student, “Do you text while driving, even though you are not supposed to?” Based on the survey, the administrator estimates that only 2% of students with parking passes text while driving. What potential bias is present in the design of this survey and what is the likely direction of the bias?

• The sample proportion is likely an underestimate of the population proportion due to response bias.

• The sample proportion is likely an underestimate of the population proportion due to undercoverage.

• The sample proportion is likely an underestimate of the population proportion due to nonresponse.

• The sample proportion is likely an overestimate of the population proportion due to response bias.

• The sample proportion is likely an overestimate of the population proportion due to undercoverage.

Tanya wants to know the percent of people likely to attend the upcoming musical at school. She asks each person in the musical how many people they know who are coming to make a prediction. Why is this sample biased?

• Drama students are more likely to lie.

• Musicals are better attended than plays.

• The drama teacher was not asked.

• The sample is not random and not representative of the entire school population.

Answer explanation

The sample is not random and not representative of the entire school population, as it only includes people involved in the musical, leading to bias.

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:

• Random Sample

• Convenience Sampling

• Voluntary Response

• Systematic Sampling

Why should samples be randomly selected?

• for control

• to reduce bias

• so we don't get the same answers from everyone

Mr. Brodie stands at the Auditorium door and asks students as they come in, "How do you get to school?" From this he concludes that 84% of students drive to school. What type of sample is this?

• Simple Random Sample

• Convenience Sample

• Voluntary Response Sample

• Stratified Sample

The owner of a candy factory wants to check the quality of the product at her two locations. The candy is packed in cases of 24 boxes each. What is the BEST sampling method to ensure the sampling method is representative?

• Cluster Sample

• SRS

• Stratified Random Sample

• Systemic Random Sample