If three variables were changed at one time, what would happen to the accuracy of the conclusions made for an experiment?

You can do the following: conduct an experiment, obtain a result, examine the process; change one variable, and reasonably, the change in one variable accounts for the difference in result; change three variables, and obtain a different result; you know that the change in ONE of the three variables resulted in a different outcome, but which of the three you changed? Therefore, you will need to conduct three independent experiments to determine which variable caused the change.

It is generally advised to change one variable at a time in experiments to accurately assess its impact on the outcome. Changing three variables at once would likely decrease the accuracy of the conclusions made because it would be difficult to determine which variable or combination of variables caused the observed effects. This approach makes it challenging to isolate the individual effects of each variable on the outcome, potentially leading to confounding results and unreliable conclusions.