The second step in looking at the correlation between the two points on a scatter plot is to take the difference between the points. This difference can be a positive number or a negative number, depending on the magnitude of one of the points. A positive correlation means that the value of one variable tends to follow the value of another. A negative correlation means that the value of one variable tends to deviate from the value of another variable. This difference is called a correlation coefficient.
The correlation coefficient is different from a simple linear relationship, because the values of different variables tend to vary from one another. If you have a correlation coefficient of one with age, you can be fairly certain that the value of the other variable, blood pressure, will also follow that of age. If, however, you find a correlation coefficient of -1 between the two variables, this is usually considered very strong evidence that there is no significant relationship. In other words, there is no statistical relationship between the two variables.
Students who are interested in learning more about how to use correlation in their studies may also benefit from study correlation. One approach is to find out how many variables are being studied when the graph is being drawn. If there are a lot of variables being studied, the correlation coefficient will be high. On the other hand, if there are only a few variables being studied, the correlation will be low. This is another reason why it is important to look at the data more carefully.
When students learn how to study scatter plots, they may see that their results show that a low correlation can indicate an absence of correlation. This means that there is no significant relationship between the variables. However, this situation can also indicate the presence of an inverse relationship, which indicates that a weak relationship does exist.
This may suggest that the variables may be related in a very simple relationship but not in a statistically significant way. A simple relationship may indicate that the value of one variable tends to decrease with age while the other variable increases.
Students can be quite surprised to learn that the plots of multiple variables can be quite different. For example, a study of the correlation between blood pressure and age can show a positive relationship. However, if a student were to compare the scatter plot with a plot showing the values of cholesterol, there can be an obvious negative correlation that strongly suggests that cholesterol is not related to blood pressure at all.
Students are able to use the study of correlation analysis to understand the nature of the relationship that exists between variables. By analyzing scatter plots and other scatter chart results, students are able to create better methods for making sense of their data and learn how to interpret and manipulate the results in their own research.
There are many uses for scatter plots. For example, students can learn how to make a correlation chart to show the relationship between variables, such as the relationship between cholesterol and blood pressure. They may then be able to draw their own conclusions about whether or not the relationship between cholesterol and blood pressure exists.
Students can also analyze the data in order to understand the relationships that are present between other variables. If the values of one variable tend to increase with the values of another variable, the relationship between the variables may be determined by a series of points on a plot.
Students can also use scatter charts to examine the relationships among their own data, whether it is from a controlled experiment, a correlation chart, or from the real world. In the case of an experiment, they may find that there is a significant relationship between the variables.