1. a mathematical equation that predicts how a physical phenomenon will behave independent variable 2. a predicted experimental outcome based on prior knowledge and experience. scientific theory 3. the variable that is changed on purpose by the scientist. qualitative data 4. the variables that must be kept constant so as not to bias or influence the results quantitative data 5. data that is descriptive rather than numerical scientific law 6. data that is numerical hypothesis 7. a well tested explanation for why a physical phenomenon occurs control variable