ShmoopTube

00:04

Scatter Plots and Equations of Lines, a la Shmoop.

00:09

Working for tips is hard.

00:10

Especially when you're the Medusa family's private hairdresser.

00:16

Shana's first weeks really bite.

00:21

The only thing keeping her going is the snake haircutting gloves advertised on TV.

00:26

It's a niche market.

00:30

To see when she'll be able to buy the gloves,

00:32

Shana tracks her tips in a scatter plot to see if there's a trend.

00:37

Scatter plots display two-variable data and make predictions based on that data.

00:45

Shana makes "weeks" her independent variable... the variable that isn't influenced by anything...

00:52

and "tips" her dependent variable.

00:55

For example, we can see that in week 2, Shana earned about $125...

01:00

...and in week 18, she earned about $165. Before taxes.

01:11

We can see Shana's tips are increasing, which means there is a Positive Correlation...

01:16

...or, as one variable increases so does the other.

01:21

Negative Correlation looks like this.

01:25

No Correlation looks like this.

01:27

Shana uses the line of best fit to predict

01:31

that, after 20 weeks, she will make approximately $170.

01:36

With the help of her scatter plot, Shana decides

01:38

those snake-proof gloves will be a worthy investment...

01:41

Which is good, because the twins just walked in for their first haircut.

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