Quadratic Regression

Linear & Quadratic Regression using Desmos

I can determine an equation of the curve of best fit, using a graphing utility, given a set of no more than 20 data points in a table, graph, or practical situation

Poll

How are you feeling today?

• Excellent, Ready to Learn

• Good, Ready to Learn

• Sleepy and Ready to Learn

• Not So Good and I'm still gone learn today!

Today, we will review:

• Line & Curve of Best Fit

• Quadratic Regression

• Regressions using Desmos

Line of Best Fit

A line of best fit (or trend line) is a straight line that best represents the data on a scatter plot. Depending on the strength of the correlation, this line may pass exactly through all of the points, some of the points, or none of the points. However, it always represents the general trend of the of the data.

Line of Best Fit Correlations

Curve of Best Fit

A curve the best approximates the trend on a scatter plot. If the data appears to be quadratic, we perform a quadratic regression to get the equation for the curve of best fit.

Regression in Desmos

• Click the plus sign in the top left corner

• Add item, table and enter data

• In next row, enter equation of reference

• Add a squiggle ~ in place of the equal

• Use the residuals (plot) to get the coefficients for the equation

Multiple Choice

What equation best represents this data set?

{(−4, −5), (−3, −8), (−2, −9), (−1, −8), (0, −5), (1, 0.5)}

• $$y=1.04x\ +4.84$$

• $$y=1.04x-4.84$$

• $$y=1.04x^2+4.21x-4.84$$

• $$y=1.04x^2+4.21x+4.84$$

Multiple Choice

Using the equation of the line of best fit from problem 1, which number is the best prediction of output when the input is -1.5?

• -8.815

• -2.5

• 0.865

• 7.18

Poll

Do you have enough information to try practice problems?

• Yes, I took notes.

• Yes, I will re-watch the recording if I have questions.

• No, I need to re-watch the video to get the steps.

• No I didn't understand the concept.