WorksheetsLessons 4.5 to 4.9 Practice Quiz
Total questions: 14
Worksheet time: 7mins
Researchers in Kisumu, Kenya, wanted to investigate whether there was a link between the presence of garbage dumps and the number of flies in various neighborhoods. The city was divided into 60 grid cells using GPS. Twelve cells with garbage dumps and twelve cells without garbage dumps were randomly chosen, and the fly population was estimated in each cell. What type of study was performed, and what is the response variable?
An experiment was performed, and the response variable is the presence of garbage dumps.
An experiment was performed, and the response variable is the fly population.
A census was performed, and the response variable is the association between garbage dumps and fly population.
An observational study was performed, and the response variable is the presence of garbage dumps.
An observational study was performed, and the response variable is the fly population.
Spelling instruction is a key part of early education. Two common approaches are the look-cover-write-check method and the use of spelling games. In the look-cover-write-check method, children look at a word, cover it, write it from memory, and then check their spelling. In spelling games, children practice spelling words through interactive activities. A study is planned to compare the effectiveness of these two methods. Children will be randomly assigned to either the look-cover-write-check method or the spelling games method. To account for differences in reading ability, researchers will block by reading level. Why is it not possible to implement double-blinding in this study?
The children will know their own reading levels.
The children will know whether they used look-cover-write-check or spelling games.
The person assessing the spelling results will know the children’s reading levels.
The person assessing the spelling results will know which method each child used.
The researcher will know the children’s reading levels and assigned methods.
Researchers are interested in the effect of roadside lighting on the activity of nocturnal insects. Along 15 stretches of highway, one side of each stretch was randomly assigned to have streetlights turned on at night, while the other side had no lighting. After two months, the number of nocturnal insects was counted on both sides of each stretch. Which of the following best describes the design of this study?
An experiment using a matched-pairs design
An experiment using a randomized block design
An experiment using a completely randomized design
A sample survey using systematic sampling
A sample survey using simple random sampling
Researchers observed that migrating geese often collide with wind turbines, leading to injuries or fatalities. To address this, the Green Energy company began painting the turbine blades with bright colors on all new turbines installed in the last three years. A recent survey found that significantly fewer injured or dead geese were found near turbines with painted blades compared to those without. What can be inferred from this study?
The use of brightly painted blades directly reduces the risk of turbine collisions.
There is an association between painted blades and the number of turbine collisions, but not necessarily a causal relationship.
There is an association between the presence of painted blades and the number of turbine collisions, but not a correlation.
There is no association between painted blades and the number of turbine collisions.
These findings can be applied to all species of migrating birds.
A research team wants to evaluate the effectiveness of two different study techniques for improving exam scores. They recruited 150 students from a single college who volunteered to participate. Seventy-five students were randomly assigned to use technique X, and the other seventy-five used technique Y. After a week, all students took the same test, and their scores were compared. To which group is it most reasonable to generalize the findings of this experiment?
All college students
All students from this college
All students from this college who use similar study techniques.
All students from this college who are similar to those who volunteered for the experiment.
All people who are the same age as the participants.
A study tracked over 4,000 adults for three years to examine the relationship between the timing of physical activity and cholesterol levels. Participants recorded the time of day they exercised and had their cholesterol measured during regular clinic visits. The results showed that those who exercised in the evening had higher cholesterol levels compared to those who exercised in the morning. What are the explanatory and response variables in this study?
Explanatory: cholesterol level; Response: time of day of exercise
Explanatory: time of day of exercise; Response: cholesterol level
Explanatory: age; Response: cholesterol level
Explanatory: overall physical activity; Response: cholesterol level
A study tracked over 4,000 adults for three years and found that those who exercised in the evening had higher average BMI scores than those who exercised in the morning. Participants reported their daily routines and attended regular health assessments. What is a potential confounding variable in this study?
Sleep duration
Brand of water bottle
Favorite movie genre
Number of siblings
A study tracked over 4,000 adults for three years and found that those who exercised in the evening had higher average BMI scores than those who exercised in the morning. Participants reported their exercise times and attended regular health assessments. What is a possible confounding variable that could explain the association between evening exercise and higher BMI?
People who exercise in the evening may have more sedentary jobs during the day.
People who exercise in the evening are more likely to use public transportation.
People who exercise in the evening tend to wear brighter workout clothes.
People who exercise in the evening are more likely to own pets.
A recent observational study of more than 5,200 adults found that morning workouts may be better for weight loss. Participants wore fitness trackers over a period of two years and also attended regular health check-ins at a doctor’s office. The researchers found that people who exercised early in the morning tended to have lower body mass index (BMI) scores than those that exercised later in the day. Explain how the confounding variable you identified could influence the response variable (BMI).
Healthier diets can reduce BMI independently of workout time.
Owning fitness trackers lowers BMI directly.
Listening to music during workouts increases BMI.
Living closer to gyms increases BMI.
A group of researchers wanted to find out if the type of background music (classical or pop) affects students' concentration while studying. They randomly assigned 30 students to listen to classical music and 30 students to listen to pop music while completing a concentration task. The researchers then compared the scores of the two groups. Why is this research classified as an experiment rather than an observational study?
Because the researchers assigned students to different music types as part of the study
Because the researchers observed students in their natural study environments
Because the study only involved collecting survey data
Because the researchers did not influence the students' study conditions
A group of 80 high school students participated in a study to determine if the format of reading material (e-book or traditional textbook) influences their understanding of the content. Students were randomly assigned to either read a chapter from an e-book or from a traditional textbook. After reading, all students completed a quiz to assess their understanding. What are the experimental units and the treatments in this experiment?
Experimental units: the students; Treatments: e-book vs. traditional textbook formats
Experimental units: the quizzes; Treatments: high vs. low scores
Experimental units: the chapters; Treatments: quiz vs. no quiz
Experimental units: the teachers; Treatments: assigned vs. not assigned
A researcher wants to study whether the format of reading material (digital or print) influences reading comprehension among high school students. She has 80 students and needs to assign them to two groups: one group will read on a digital device and the other on printed paper. What is the best way to randomly assign students to the two groups?
Use a random number generator to assign each student to either the digital or print group, making sure there are 40 students in each group
Assign students to groups based on their seating arrangement in the classroom
Allow students to pick which group they want to join
Group students by their birth months
A restaurant manager wanted to test if offering a free appetizer coupon to some tables would increase the average amount spent. For each table, the manager rolled a die: even number = offer coupon; odd number = do not offer coupon. Was random assignment used in this experiment?
Yes, tables were randomly assigned to coupon/no-coupon groups using the die roll
No, because the manager chose based on the group size
No, because only survey data were collected
Yes, a random sample makes it experimental
A bar manager wanted to test if offering a complimentary appetizer to customers would increase the average amount spent per table. For each table during one evening, the manager rolled a die: even = no appetizer; odd = offer a complimentary appetizer. The group offered the appetizer had a significantly higher average bill. What is the most appropriate conclusion?
Offering a complimentary appetizer causes customers to spend more on average in this bar setting
The offer is only associated with higher spending; causation cannot be determined
The result applies to all bars and all customer groups everywhere
No conclusion can be made because there was no random assignment
