Fundamentals of Math

Fundamentals of Mathematics

To create a scatterplot, like the other graphs, begin by drawing and labeling the and -axis. Then divide up each axis into intervals so that the range encompasses the minimum and maximum values of the data in the dataset. Next, draw the points on the graph. Finally, step back and observe your work.

Example 6.6

Directions: Using the data from Table 6.1, create a bar chart that shows the relationship between a patient's age and their sodium to potassium ratio and then infer if you think age is a predictor of this ratio.

Again, a more in-depth study of descriptive statistics would dive into all the different things to look at when observing a scatterplot, but as we did with the histogram - we will continue to focus on the big picture. With scatterplots, you are focusing in on if your points form a pattern, like a line, and then what is the slope of the line. A positive slope would indicate as the -variable is increasing, the - variable also increases (or vice-versa) whereas a negative slope shows that as the -variable increases the -variable decreases (or vice-versa) - the inverse relationship. Something like that is usually a good sign that one variable is a possible predictor of the other variable, or at least some underlying factor exists between both variables. However, in this particular instance, we see no generalized line is formed, and the points are pretty scattered low to high (what we expected based on the histogram). Therefore, this is showing us that a relationship likely does not exist at all. In other words, we cannot use the patient’s age to help us predict the sodium to potassium ratio in patients.

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