Independent vs Dependent Variable Quiz
Questions: 16 · 10 minutes
1. A researcher wants to test whether screen brightness affects battery life. Which design correctly manipulates the independent variable and measures the dependent variable?
Use one brightness setting and compare several phone brands by screen size.
Set phones to different brightness levels and record how long each battery lasts.
Change battery capacity and record the brightness selected by each user.
Measure users’ preferred brightness and hold battery duration constant.
2. Which hypothesis correctly identifies hours of tutoring as the independent variable and test performance as the dependent variable?
As hours of tutoring increase, students’ test scores will change.
Tutoring quality will stay constant because test performance controls it.
Students with different test scores will be assigned different amounts of tutoring.
Hours of tutoring and test scores will both be held constant.
3. A gardener gives tomato plants 0, 5, or 10 grams of fertilizer and records their height after six weeks. What is the independent variable?
The height of each plant after six weeks
The six-week growing period
The tomato plants used in the study
The amount of fertilizer given
4. Which statement best defines a dependent variable?
It is the condition assigned by the researcher before data collection.
It is the group used as a comparison baseline.
It is a characteristic kept identical across all conditions.
It is the outcome measured to see whether it varies with the independent variable.
5. A researcher defines background-noise level as 40, 60, or 80 decibels while participants complete a reading task. What is the operational form of the independent variable?
The reading passages used in the task
Participants’ reading scores
The three specified decibel levels
The room where testing takes place
6. A graph shows practice time predicting typing speed. Following the usual graphing convention, which variable belongs on the vertical y-axis?
Practice time, because it is recorded first
Practice time, because it is the predictor
Typing speed, because it is the dependent variable
Typing speed, because it must be experimentally controlled
7. Which statement best defines an independent variable in a typical experiment?
It is an uncontrolled influence that offers an alternative explanation.
It is the outcome recorded after the experimental conditions are applied.
It is any factor held constant across all experimental groups.
It is the factor the researcher deliberately changes to examine its effect.
8. Participants receive caffeine doses of 0, 50, 100, or 200 milligrams before an attention task. What do those four doses represent?
Four measurements of the dependent variable
Four control variables used to standardize the task
Four levels of the independent variable
Four possible confounders in the study
9. A student changes water temperature and measures how long a sugar cube takes to dissolve. Which pairing correctly identifies the variables?
Independent: dissolving time; dependent: water temperature
Independent: water temperature; dependent: dissolving time
Independent: sugar cube; dependent: amount of water
Independent: amount of water; dependent: container type
10. A teacher compares a new teaching method used in a morning class with a traditional method used in an afternoon class, then measures exam scores. Why might class time be a confounding variable?
It is the main outcome the teacher intends to measure.
It is another name for the exam-score dependent variable.
It is identical for both classes and therefore controls the comparison.
It changes alongside teaching method and could also affect exam scores.
11. In a study of how light duration affects plant growth, every plant receives the same amount of water. What role does the amount of water play?
It is the independent variable because the researcher supplies it.
It is the dependent variable because plants absorb it.
It is a control variable because it is kept consistent.
It is the outcome because it may influence growth.
12. Students are randomly assigned to study with instrumental music or in silence, and their recall scores are compared. The music group earns higher scores. What outcome changed across the independent-variable conditions?
Music condition, the dependent variable
Recall score, the dependent variable
Random assignment, the independent variable
Study environment, the measured outcome
13. Researchers assign participants to sleep for either six or eight hours, then measure their reaction time the next morning. What is the dependent variable?
The assigned amount of sleep
Reaction time the next morning
The participants assigned to each sleep group
The time of day when testing occurs
14. An observational study asks whether weekly exercise time predicts resting heart rate. No exercise schedule is assigned. Which variable is treated as the dependent variable in the research question?
Resting heart rate
The number of participants recruited
Weekly exercise time
Whether the study is observational
15. In the question “Does the number of practice problems completed affect the score on a mathematics test?”, what is the dependent variable?
The mathematics test score
The number of practice problems completed
The amount of mathematics content in the course
The students’ assigned practice materials
16. Study A asks whether stress predicts sleep duration. Study B asks whether sleep duration predicts next-day stress. What does this show about variable roles?
A variable’s role can change according to the specific research question.
Stress must be independent in both studies because it can influence behavior.
Sleep duration must be dependent in both studies because it is measured in hours.
Neither study can use independent or dependent variables unless participants are randomly assigned.