Vocabulary
A numerical value about a sample.
What is a statistic?
A school counselor emails every junior a set of questions about how many hours they sleep on school nights and how stressed they feel. She records the responses and calculates averages.
A reporter stands outside a grocery store and asks the first 30 shoppers who walk past whether they support a new bus route.
What is a convenience sample?
A city official wants to know the average commute time of all workers in the city. She randomly selects 400 workers and records their commute times. Identify the population.
What is all workers in the city?
A numerical value about a population.
What is a parameter?
A park ranger sits near a trailhead for a week and tallies how many hikers wear helmets while biking, without speaking to anyone or changing anything about the trail.
What is an observational study?
A principal assigns each of the 1,200 students in her school a number, then uses a random number generator to pick 60 numbers. Those 60 students are surveyed about the lunch menu.
What is a simple random sample? (SRS)
A school has 1,500 students. A survey of 150 randomly chosen students finds that 62% of them ride the bus. Records show that 58% of all 1,500 students ride the bus. 62% is a . . .
a. statistic
b. placebo
c. parameter
d. confounding variable
What is statistic?
Involves organizing, displaying, and summarizing data.
What is descriptive statistics?
An engineer wants to know how long customers will wait in line at a new coffee shop with two registers versus three. Rather than build the shop, she writes a program that generates random customer arrival times and service times, then runs it 10,000 times for each setup.
What is a simulation?
A district has 30 elementary schools. A researcher randomly selects 4 of the schools and surveys every teacher at those 4 schools about class size.
What is a cluster sample?
A teacher records the scores of all 28 students on a unit test in a spreadsheet and reports that the class mean was 81 and the median was 84. This an example of what kind of statistic.
What is descriptive statistic?
Fake treatment.
What is a placebo?
A coach wants to know whether a new warm-up routine reduces injuries. She randomly assigns half the players on her team to use the new routine and half to use the old one, then tracks injuries across the season.
What is an experiment?
A quality inspector tests every 20th phone coming off the assembly line, starting with a randomly chosen phone from the first 20.
What is a systematic sample?
A researcher gives 100 adults a memory test and asks how many cups of coffee each drinks per day. Participants were recruited from a local workplace, and the heavy coffee drinkers were mostly employees who had just started their shifts, while the light drinkers were mostly retirees visiting the building’s community center. State the confounding variable in this study.
What is age?
Using sample data to draw conclusions about the population.
What is inferential statistics?
A teacher randomly splits her class in half. One half reads a calming article before the period, the other reads nothing. Afterward, every student fills out a short questionnaire rating their stress level, and she compares the two groups’ averages.
What is an experiment?
A college has 4,000 students: 40% freshmen, 30% sophomores, 20% juniors, and 10% seniors. To survey 200 students, an administrator separates the student list by class year and randomly selects students from each year in proportion to its size.
What is a stratified sample?
A school district has 20 high schools. To learn about student screen time, a researcher randomly selects 5 of the schools and surveys every student at those 5 schools. What sampling technique is used here.
What is a cluster sample?