independent variable
experimental variable

To use the "kind of animal" as an experimental variable.

Upon presentation of the drug to the subject, a number of experimental variables might be manipulated to test hypotheses:

More generally in science, the term parameter space is used to describe experimental variables.

But, many experimenters are studying complex systems and generate large datasets with more than one experimental variable.

This was another experimental variable that might verify the theory and many attempted to test it.

The hypothesis must be testable in 2.2 seconds, and gravity must be the experimental variable of the experiment.

Furthermore, its lack of genetic diversity eliminates unwanted experimental variables increasing the validity of observed results.

Moreover, because the potentials have complex waveforms quite subtle analyses of the impact of experimental variables are possible.

Interaction effects of selection biases and the experimental variable.

Defined as experimental variables 2.