What is a Scatter Plot and When to Use It
A scatter plot is a special type of graph designed to show the relationship between two variables. With regression analysis, you can use a scatter plot to visually. After collecting a set of data, the data points for two variables can be plotted on a graph Even though most of the graphs in Figure show curves . it also has a very different meaning from a line of best fit on a scatter graph (see Section Scatterplots display these bivariate data sets and provide a visual representation of the Correlation Patterns in Scatterplot Graphs. Examining.
If the line goes from a high-value on the y-axis down to a high-value on the x-axis, the variables have a negative correlation.
A perfect positive correlation is given the value of 1. A perfect negative correlation is given the value of If there is absolutely no correlation present the value given is 0. The closer the number is to 1 or -1, the stronger the correlation, or the stronger the relationship between the variables.
The closer the number is to 0, the weaker the correlation. So something that seems to kind of correlate in a positive direction might have a value of 0.
Scatter Plot: Is there a relationship between two variables?
An example of a situation where you might find a perfect positive correlation, as we have in the graph on the left above, would be when you compare the total amount of money spent on tickets at the movie theater with the number of people who go. This means that every time that "x" number of people go, "y" amount of money is spent on tickets without variation.Describing a scatterplot
An example of a situation where you might find a perfect negative correlation, as in the graph on the right above, would be if you were comparing the amount of time it takes to reach a destination with the distance of a car traveling at constant speed from that destination.
On the other hand, a situation where you might find a strong but not perfect positive correlation would be if you examined the number of hours students spent studying for an exam versus the grade received.
This won't be a perfect correlation because two people could spend the same amount of time studying and get different grades.
Correlations may be positive risingnegative fallingor null uncorrelated. If the pattern of dots slopes from lower left to upper right, it indicates a positive correlation between the variables being studied. If the pattern of dots slopes from upper left to lower right, it indicates a negative correlation.
A line of best fit alternatively called 'trendline' can be drawn in order to study the relationship between the variables. An equation for the correlation between the variables can be determined by established best-fit procedures.
Scatter plot - Wikipedia
For a linear correlation, the best-fit procedure is known as linear regression and is guaranteed to generate a correct solution in a finite time. No universal best-fit procedure is guaranteed to generate a correct solution for arbitrary relationships.
A scatter plot is also very useful when we wish to see how two comparable data sets agree to show nonlinear relationships between variables. The scatter diagram is one of the seven basic tools of quality control. The researcher would then plot the data in a scatter plot, assigning "lung capacity" to the horizontal axis, and "time holding breath" to the vertical axis.
The scatter plot of all the people in the study would enable the researcher to obtain a visual comparison of the two variables in the data set, and will help to determine what kind of relationship there might be between the two variables.