Unit 5, Lesson 23
Observing More Patterns in Scatter Plots
Accelerated 7
23.1
Warm-up
Find groups of 2 or 3 scatter plots that share something in common that the others do not. What do they have in common?
Plot A, points start at 0 comma 40 and trend down and to the right.
Plot B has 2 sets of points, 1 starts near the origin and trends up and to the right. The second starts near 3 comma 25 and trends up and to the right.
Plot C has 2 sets of points, 1 starts near the origin and trends up and to the right. The second starts near the origin and trends down and to the right
Plot D points starts near 0 comma 40 and trends down and to the right toward 24 negative 20, but there are no points between x = 6 and x = 12.
23.3
Activity
Is there an association between the weight of an animal’s body and the weight of the animal’s brain?
A scatter plot has been made using the data in the table. Identify any outliers?
| animal | body weight (kg) | brain weight (g) |
|---|---|---|
| cow | 465 | 423 |
| grey wolf | 36 | 120 |
| goat | 28 | 115 |
| donkey | 187 | 419 |
| horse | 521 | 655 |
| potar monkey | 10 | 115 |
| cat | 3 | 26 |
| giraffe | 529 | 680 |
| gorilla | 207 | 406 |
| human | 62 | 1,320 |
| rhesus monkey | 7 | 179 |
| kangaroo | 35 | 56 |
| sheep | 56 | 175 |
| jaguar | 100 | 157 |
| chimpanzee | 52 | 440 |
| pig | 192 | 180 |
- After removing the outliers, does there appear to be an association between body weight and brain weight? Describe the association in a sentence.
- Using a piece of pasta and a straightedge, fit a line to your scatter plot, and estimate its slope. What does this slope mean in the context of brain and body weight?
- Does the fitted line help you identify more outliers?
Student Lesson Summary
Sometimes a scatter plot shows an association that is not linear:
In this scatter plot, the data initially shows a negative trend then later a positive trend. Because the variables appear to be associated, but not in a linear way, we call this a non-linear association. In later grades, you will study functions that can be models for non-linear associations.
Sometimes in a scatter plot we can see separate groups of points.
A scatterplot with two groups of points. The first begins near the origin and trends up and to the right toward 8 comma 13. Second group begins near 3 comma 25 and trends up and right toward 9 comma 45.
A scatterplot with two groups of points. The first begins near the origin and trends up and to the right toward 8 comma 13. Second group begins near 3 comma 25 and trends up and right toward 9 comma 45. Each group is circled.
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