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).
The easiest way to determine your eye dominance for those who are new to bullseye shooting would be to reach out your arms in front of you, bring your hands together with the palms facing outwards and form a small 1 opening between the web of both hands.