In this function, y is the dependent variable and x is the independent variable. Variable used in an experiment or modelling can be divided into three types:  dependent variable ,  independent variable , or other.
About 70% of men have an eye dominance that matches their handedness. BUT, 30% do not. Most right handers have a dominant right eye and the bulk of southpaws a dominant left. These are the people who are well advised to shoot both eyes open (assuming that they are shooting from their strong shoulder).
Most people have a dominant eye, or one eye that works a little bit harder than the other. Even though you use both eyes to look at an object, you use your dominant eye more. Eye dominance is important for certain sports which require accurate aim.