Text begins In science, the scatterplot is widely used to present measurements of two or more related variables. It is particularly useful when the values of the variables of the y-axis are thought to be dependent upon the values of the variable of the x-axis. In a scatterplot, the data points are plotted
but not joined. The resulting pattern indicates the type and strength of the relationship between two or more variables. Chart 5.6.1 is an example of a scatterplot. Car ownership increases as the household income increases, showing that there is a positive relationship between these two variables.
Data table for Chart 5.6.1
The pattern of the data points on the scatterplot reveals the relationship between the variables. Scatterplots can illustrate various patterns and relationships, such as:
Linear or non-linear relationshipWhen the data points form a straight line on the graph, the relationship between the variables is linear, as shown in Chart 5.6.2, Part A. When the data points don’t form a line or when they form a line that is not straight, like in Chart 5.6.2, Part B, the relationships between variables is not linear. Data table for Chart 5.6.2
Data table for Chart 5.6.2
Positive or negative relationshipIf the points cluster around a line that runs from the lower left to upper right of the graph area, then the relationship between the two variables is said to be positive or direct (Chart 5.6.3, Part A). If the points cluster around a line that runs from the upper left to the lower right of the graph area, then the relationship is said to be negative or inverse (Chart 5.6.3, Part B). Data table for Chart 5.6.3
Data table for Chart 5.6.3
Concentration or spread of data pointsData points can be close together (Chart 5.6.4, Part A) or spread widely across the graph area (Chart 5.6.4, Part B). Data table for Chart 5.6.4
Data table for Chart 5.6.4
Presence of outliersBesides portraying relationships between the variables, a scatterplot can also show whether or not there are any outliers in the data. Outliers are data points that are far from the other points in the data set, like the two points in red in Chart 5.6.5. Data table for Chart 5.6.5
Data table for Chart 5.6.5
Report a problem on this page Is something not working? Is there information outdated? Can't find what you're looking for? Please contact us and let us know how we can help you. Privacy notice Date modified: 2021-09-02How would you describe the relationship between two variables on a scatter plot?We often see patterns or relationships in scatterplots. When the y variable tends to increase as the x variable increases, we say there is a positive correlation between the variables. When the y variable tends to decrease as the x variable increases, we say there is a negative correlation between the variables.
What are the two variables in a scatter plot called?A scatter plot is a plot of the values of Y versus the corresponding values of X: Vertical axis: variable Y--usually the response variable. Horizontal axis: variable X--usually some variable we suspect may ber related to the response.
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