IM 8.6.5 Lesson: Describing Trends in Scatter Plots

Which one doesn’t belong?

Experiment with finding lines to fit the data. Drag the points to move the line. You can close the expressions list by clicking on the double arrow.

Here is a scatter plot. Experiment with different lines to fit the data (drag the green points to move the line). Pick the line that you think best fits the data.

Here is a different scatter plot. Experiment with drawing lines to fit the data. Pick the line that you think best fits the data. Compare it with a partner’s.

Compare them with a partner’s line. In your own words, describe what makes a line fit a data set well.

The scatter plots both show the year and price for the same 17 used cars. However, each scatter plot shows a different model for the relationship between year and price.

For how many cars does the model in Diagram A make a good prediction of its price?

For how many cars does the model underestimate the price?

For how many cars does it overestimate the price?

For how many cars does the model in Diagram B make a good prediction of its price?

For how many cars does the model underestimate the price?

For how many cars does it overestimate the price?

For how many cars does the prediction made by the model in Diagram A differ by more than $3,000?

What about the model in Diagram B?

Which model does a better job of predicting the price of a used car from its year?

Is this line a good fit for the data?

Explain your reasoning.

Draw a line that fits the data better.

Is this line a good fit for the data? Explain your reasoning.

Draw a line that fits the data better.

These scatter plots were created by multiplying the -coordinate by 3 then adding a random number between two values to get the -coordinate. The first scatter plot added a random number between -0.5 and 0.5 to the -coordinate. The second scatter plot added a random number between -2 and 2 to the -coordinate. The third scatter plot added a random number between -10 and 10 to the -coordinate.

Draw a line that fits the data

Draw a line that fits the data

Draw a line that fits the data

Explain why some lines were easier to draw than others.