Final answer:
An antecedent variable is one that occurs before other variables in an experiment and may influence the outcome. These variables are important to identify and control for to ensure the validity of experimental results.
Step-by-step explanation:
A variable that occurs prior to all other variables and that may affect other independent variables is called an antecedent variable. In the context of scientific experiments, independent variables are the ones that are manipulated to test their effect on the dependent variables, the outcomes that researchers measure. However, antecedent variables are those that exist before the study begins and can influence the results. They might provide a context or set conditions that affect how the other variables interact, and controlling for these antecedent variables can be crucial to the design of an experiment. It is important that researchers are aware of potential antecedent variables that may impact the validity of the experiment's findings.