Question

Check all factors in the the lab procedure and data sheet that change from trial to trial.

immunity rate (percentage)

initial number of people with the disease

number of people in the population

final number of people with the disease

rate of disease spread

Answer 1

Based on a typical controlled lab setup, the things that will change from trial to trial are:

- Immunity rate (percentage) — usually the independent variable you change between trials.
- Final number of people with the disease — the dependent (measured) outcome that will vary as a result.

The following are usually held constant across trials (controls), unless your procedure says otherwise:

- Initial number of people with the disease — normally kept the same so outcomes are comparable.
- Number of people in the population — usually fixed so population size doesn't confound results.
- Rate of disease spread — typically kept constant (to isolate the effect of immunity), though some experiments vary this as a separate factor.

If your specific lab varies a different parameter (e.g., initial infected or spread rate), tell me which variables your procedure says are changed and I’ll mark them accordingly.