Original Project
Control of Variables
If more than one variable changes at the same time in an experiment, the outcome of the experiment may not be cl…
Item CV024005: An experiment in which variable X is allowed to vary and variables Y and Z are held constant could tell you if variable X has an effect on the result of the experiment.
A student thinks that there are three variables (X, Y and Z) that may affect the result of her experiment.
What should the student do to find the effect of variable X on the result of the experiment?
- Change variable X and keep variables Y and Z the same.
- Change variables Y and Z at the same time and keep variable X the same.
- Change variable X and Y at the same time and keep variable Z the same.
- Change variables X, Y, and Z at the same time.
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 2371 |
6–8 n = 1284 |
9–12 n = 1078 |
Male n = 1164 |
Female n = 1170 |
English n = 2084 |
Other n = 227 |
||
| A. | Change variable X and keep variables Y and Z the same. | 51% | 44% | 59% | 53% | 49% | 52% | 40% |
| B. | Change variables Y and Z at the same time and keep variable X the same. | 27% | 29% | 25% | 24% | 30% | 27% | 26% |
| C. | Change variable X and Y at the same time and keep variable Z the same. | 11% | 13% | 9% | 11% | 10% | 10% | 16% |
| D. | Change variables X, Y, and Z at the same time. | 11% | 14% | 7% | 11% | 11% | 10% | 18% |