Sample Who?
The entire group a study aims to understand.
What is the population?
A sample made by choosing people who are easiest to reach.
What is a convenience sample?
A sampling method in which every possible group of a fixed size has an equal chance of selection.
What is an SRS (or Simple Random Sample)?
A systematic tendency for a sampling method to overrepresent or underrepresent certain members of a population.
What is (sampling) bias?
A poll lets anyone choose whether to answer, and people with especially strong opinions are more likely to participate.
What is a voluntary-response sample?
A smaller group selected from a population to provide data.
What is a sample?
A researcher asks a basketball coach to select the players who seem most representative of the team.
What is a judgement sample?
The natural difference that occurs when different random samples from the same population produce different results.
What is sampling variability?
A study of school transportation surveys only students who drive themselves to school. Reason for the issue with this method.
What is bias in sampling, because students using other forms of transportation are excluded?
One study uses a random-number generator to choose students; another allows anyone to answer an online poll. The first is a ___ while the second is ____.
What is an SRS and what is voluntary-response sample?
In Scenario 1 about Cafeteria Speed Survey, the students surveyed near the cafeteria entrance are this part of the study.
What is a sample?
In Scenario 1 about Cafeteria Speed Survey, surveying the first 30 students near the entrance uses this method.
What is a convenience sample?
In Scenario 3 about Random Jersey Numbers, selecting eight different player numbers with a random-number generator is this method.
What is a simple random sample, or SRS?
In Scenario 4 about The Sleep Study, surveying only students leaving an early-morning study hall may produce this problem with estimating the amount of sleep students get. (ie - the direction of the estimate)
What is an underestimate of the amount of sleep that students get?
In Scenario 2 about Social Media Poll, students decide for themselves whether to vote on Instagram. This is the method used.
What is voluntary response sampling?
In Scenario 3 about Random Jersey Numbers, the population is this group the coach wants to describe.
What is the entire team, or all of the team’s players?
A food blogger interviews three friends who already enjoy spicy food to judge a new hot sauce. The method is especially vulnerable because the blogger selected people based on ease and personal judgment.
What is a convenience sample, or possibly a judgment sample, and why might it fail to represent all customers?
In Scenario 3 about Random Jersey Numbers, every group of eight has an equal chance because the coach assigns numbers to every player and uses this selection process.
What is random selection using a random-number generator?
In Scenario 4 about The Sleep Study, the sampled students may differ from the whole student body because they may have unusually busy schedules or different sleep habits.
What is bias in sampling, caused by an unrepresentative group?
Match each situation to its concept: Scenario 1 uses easy-to-reach students; Scenario 2 lets people choose whether to answer; Scenario 3 randomly selects eight players; Scenario 4 may systematically differ from the school; Scenario 5 changes from sample to sample.
What are convenience sample, voluntary response, simple random sample, bias in sampling, and sampling variability, respectively? (these must be in order!)
A researcher wants to learn how all McDonogh upper school students travel to school but surveys only 40 students. The 40 students and all upper school students are, respectively, these two groups.
What are the sample and the population?
Unlike a simple random sample, this method deliberately relies on someone’s opinion about which individuals seem typical or useful.
In Scenario 5 about Three Snack Samples, the percentage who like the snack changes when another group of 20 is randomly selected. This is not necessarily a mistake because of this principle.
What is sampling variability?
A sample can be large yet still give a misleading result if its selection method consistently leaves out or overrepresents certain types of people.
What is bias in sampling?
In Scenario 2 about Social Media Poll, strong opinions may be overrepresented because students who feel strongly are more likely to do this. (*we haven't explicitly learned this term yet!)
What is nonresponse bias?