We are asked to give examples of real-world situations with a positive correlation, one with a negative correlation, and a last one showing no correlation. There are lots of examples we can use, we will just illustrate one possibility. We will begin by recalling each definition, and then show an example situation.
Positive Correlation
When we see that the y values tend to increase as the x values increase, we say that the two sets of data have a positive correlation. An example is the average height of boys during their first year of life in relation to the time passed.
Negative Correlation
When we see that the y values tend to decrease as the x values increase, we say that the two sets of data have a negative correlation. One example is the temperature at which water boils in relation to the altitude. Water boils around 100 ° C at sea level, but it boils at lower temperatures the higher the altitude due to lower atmospheric pressure.
No Correlation
When we see that the y values and the x values are not related, we say that the two sets of data have no correlation. One example is the average height for students when compared to the number of students in a class.
