Scatter diagrams are particularly helpful graphs when we want to see if there is a linear relationship between two variables. Watch this video: Introduction to Linear Regression and Scatter Diagrams by ExcelIsFun
If x is the independent variable and y is the dependent variable, then we can use a regression line to predict a value for y for a given value of x. However, we only calculate a regression line if one of the variables, x, helps to explain or predict the other variable, y. This model is constructed through a process called simple linear regression. If a scatter diagram shows a linear relationship, we would like to create a model based on this apparent linear relationship. The linear relationship is strong if the points are close to a straight line, except in the case of a horizontal line where there is no relationship. In the next section, we will learn about a numerical measure, the correlation coefficient, that measures the strength and direction of the linear relationship.īecause linear patterns are quite common, we are interested in scatter diagrams that show a linear pattern. In this chapter, we are only concerned with the strength and direction of the linear relationship between the independent and dependent variables. A common chart title is independent variable vs dependent variable, using the actual names of the variables. Label the axes, including both the variable names and units.Assign the dependent variable to the vertical or y-axis. Assign the independent variable to the horizontal or x-axis.Identify the independent and dependent variables.The x-coordinate is the value of the independent variable and the y-coordinate is the value of the corresponding dependent variable. Each point on the scatter diagram represents the values of two variables. The most common and easiest way to illustrate the relationship between the two variables is with a scatter diagram.Ī scatter diagram (or scatter plot) is a graphical presentation of the relationship between two numerical variables. The amount of money earned per session is the dependent variable because its value can be determined from the value of the other variable (the number of hours per session).īefore we begin the discussion about correlation and linear regression, we need to consider ways to display the relationship between the independent variable x and the dependent variable y.The number of hours per session is the independent variable because it can be used to predict the value of the other variable (the amount of money earned per session).Here, there are two variables: the number of hours per session and the amount of money earned per session.
#Construct a scatter plot in excel plus
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