Correlation and Regression - Using Technology

Correlation and Regression - Using Technology

Author: mary daunis

to illustrate the process for finding a linear regression equation by using technology: TI83/84 calculator; Excel; Statdisk.

We can use linear regression to make predictions if the variables have a strong correlation. This packet explores the relationship between brain size and IQ and determines if an IQ can be predicted from brain size - does a bigger brain size relate to a higher IQ? If it does, then we should be able to predict IQ based on brain size. If the correlation is not strong, then the best predictor of IQ would simply be the mean, 100.
Three technology solutions are presented. The first uses a TI84 calculator. The second shows how to do a trendline using Excel. The third video illustrates the solution using Statdisk, software that was developed by Mario Triola for his Elementary Statistics textbook.

See More

Try Our College Algebra Course. For FREE.

Sophia’s self-paced online courses are a great way to save time and money as you earn credits eligible for transfer to over 2,000 colleges and universities.*

Begin Free Trial
No credit card required

28 Sophia partners guarantee credit transfer.

253 Institutions have accepted or given pre-approval for credit transfer.

* The American Council on Education's College Credit Recommendation Service (ACE Credit®) has evaluated and recommended college credit for 21 of Sophia’s online courses. More than 2,000 colleges and universities consider ACE CREDIT recommendations in determining the applicability to their course and degree programs.


Predicting IQ

The table gives brain sizes and IQs for 10 subjects. We want to find the best predicted IQ of someone with a brain size of 1275 cm3.

Brain Size (cm3)






















Should we use linear regression? We need to examine the data and decide whether regression is appropriate. If it is, we can obtain a prediction from the regression line. If it is not appropriate, we should simply use the mean IQ score as the best predictor.

Source: Elementary Statistics, 11th edition, Mario Triola

Linear Regression and the TI83/84 Calculator

Determine the linear regression line for brain size vs. IQ using the data provided. Decide whether linear regression is appropriate. What is the best predictor of IQ in this case: brain size or mean IQ?

Excel Regression

Use Excel to create a trendline -

Statdisk Regression

Use Statdisk to do linear regression -

What is the best predictor?

Based on the regression, with a brain size of 1275 cm3 we would predict an IQ of 71.8+0.0286(1275) = 108.

But since a linear relation is not supported, we would instead use the mean IQ score of 100 as the best predictor, independent of brain size.