After being subjected to clinical tests like those used to evaluate the effectiveness of prescription drugs, a popular nonprescription herbal remedy was found to be as effective in treating painful joints as is a certain prescription drug that has been used successfully to treat this condition. The manufacturer of the herbal remedy cited the test results as proof that chemical agents are unnecessary for the successful treatment of painful joints.
The statement 'The herbal remedy contains no chemical agents that are effective in treating painful joints' is an assumption required for the test results to provide the proof that the manufacturer claims they do.