When making any type of graph, one of the most important factors to consider is which variable is the independent variable, and which variable is the dependent variable. One easy way to figure out the difference between the two is to remember that the independent variable is the variable over which the experimenter has control, whereas the dependent variable is the one that changes based on how
. the independent variable changes.When graphing, the independent variable always goes on the x-axis whereas the dependent variable always goes on the y-axis. It is possible to analyze different types of data by creating a regression curve based on the data. A regression curve allows experimenters to make predictions about results based on the value of the independent variable. Regression equations are created by putting a line of best fit on the data. The line of best fit can be any of a number of different types of lines include a quadratic equation, a line or even a sinusoidal equation. The r-value shows how well the regression line is able to predict the values of the dependent variable based on the independent variable.In an experiment, the goal is to keep everything but the independent variable constant. An ideal experiment only has one independent variable. An experiment may have many dependent variables, and an experimenter may measure all of them and make regression lines for all of them. For example, an experiment may measure reaction time and cognitive ability compared to number of hours awake. In this experiment, the independent variable would be numbers of hours awake and the dependent variables would be reaction time and cognitive ability. The experiment would measure reaction time and cognitive ability of the same person after the person is awake for one hour, two hours, and continue measuring the reaction time of the person after that person stays awake for any number of hours. More reference links: http://nces.ed.gov/nceskids/help/user_guide/graph/variables.asp http://www.uncp.edu/home/collierw/ivdv.htm
