"Manipulate the results" means to intentionally change or control the outcomes or findings of something, usually for personal gain or to achieve a desired outcome. Full definition
When two journalists teamed up to see how difficult it would be to manipulate the results of Reddit, they found it easy. (policygenius.com)
If participants were using the redo button to intentionally or unintentionally manipulate results, then a difference should be detected. (journals.plos.org)
However, Realtors typically have very little training in appraisal methodologies and are in a position to manipulate the results so as to tell you what you want to hear. (caare.org)