How well do you understand the Hierarchy of Controls?
Test your knowledge of the Hierarchy of Controls by dragging the controls into the correct order. Tell us in the comments how you did.
Learn more about the hierarchy in the October 2022 issue of Safety+Health.
Post a comment to this article
Safety+Health welcomes comments that promote respectful dialogue. Please stay on topic. Comments that contain personal attacks, profanity or abusive language – or those aggressively promoting products or services – will be removed. We reserve the right to determine which comments violate our comment policy. (Anonymous comments are welcome; merely skip the “name” field in the comment box. An email address is required but will not be included with your comment.)
Title
March 14, 2023
Aww. That was too easy! Make us a harder one, with actual examples (like sizing a relief valve to prevent overpressure, or implementing a procedure to connect a grounding cable. But I really like the interactive quiz format, thank you!!
Title
July 24, 2024
Very informative publication, an educational safety guide with practical tenants applicable to any work environment!
February 3, 2025
When conducting an experiment, a control is an element that remains unchanged or unaffected by other variables. It's used as a benchmark or a point of comparison against which other test results are measured. Controls are typically used in science experiments, business research, cosmetic testing and medication testing.
For example, when a new type of medicine is tested, the group that receives the medication is called the “experimented” group. The control group, however, receives no medicine or a placebo.
By comparing the impact on those who take the medicine to those who don't, scientists can observe and measure the effects the new medication.
Related: The Scientific Method Steps (With an Example)
Variables in experiments
A controlled variable is one of three types of variables usually found in experiments. A variable is any factor, trait, or condition that can exist in differing amounts or types. The other two are independent and dependent variables.
1. Controlled variables
Controlled variables are quantities that a scientist wants to remain constant. If they were altered, it would greatly affect the experiment’s results. Most experiments have more than one controlled variable.
For example, if you are testing a new cold medicine, the controlled variable might be that the patient has a cold and a fever. If you tested someone without those two controls, your results would be inaccurate and possibly misleading.