An "independent predictor" refers to a factor or variable that can accurately predict or forecast an outcome or event on its own, without being influenced by any other factors or variables. Full definition
Maternal ratings of aggressive, explosive, sad, and moody were significant independent predictors of suicide behavior for ADHD - C, and sad and moody were predictors for ADHD - I. (link.springer.com)
Those other independent predictors of people's views include religious affiliation, age, level of education, specific science knowledge and gender. (sciencedaily.com)