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).
Sixty-five percent of people have a dominant eye that is the same as their dominant hand. That is, if they're right handed, their dominant eye is their right eye (or left eye if they're left-handed). Eighteen percent of people are like me, with their dominant eye different from their dominant hand, while 17 percent of people have no identifiable dominant eye.