Question

Explain why a trend line in a scatterplot can be used for making predictions in real-world situations.

Answer 1

Please do not copy-paste my response.

Suppose we have a set of data points that show a strong trend. As an example: let's suppose we ask 100 students what their GPA is, vs. how many hours they spend studying each night. You would expect some positive correlation (more hours studying *generally* leads to higher grades, with a few exceptions, of course)

We can take the data points, calculate a trend line. That way we have an equation that lets us input any GPA or hours of studying (within the domain, of course) and generate a predicted output.

So to answer the question more generally, a trendline lets us generate a formula that will allow us to predit the output value for any input value within the domain. This can be done for basically any real-life situation with a correlation between two or more variables.