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Exploring Bivariate Data Videos 5 videos

AP Statistics 2.4 Exploring Data
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AP Statistics: Exploring Data Drill 2, Problem 4. This coefficient shows a relationship of...what?

AP Statistics 2.5 Exploring Data
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AP Statistics 2.5 Exploring Data. Which of the following is an example of bivariate categorical data?

AP Statistics 4.3 Exploring Data
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AP Statistics 4.3 Exploring Data. We would love it if our linear correlation coefficient were what?

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AP Statistics 2.4 Exploring Data 304 Views


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Description:

AP Statistics: Exploring Data Drill 2, Problem 4. This coefficient shows a relationship of...what?

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English Language

Transcript

00:03

Here's your shmoop du jour, brought to you by Distraction.

00:06

It's usually not a good thing,

00:07

but sometimes—OOH, LOOK, A SQUIRREL!

00:11

Some of us feel like we can work better with a little distraction.

00:14

We gathered data to see if this hypothesis was true for everyone, and graphed a scatterplot data

00:19

showing "hours spent watching Hulu after dinner" on the x-axis and "hours of homework completed

00:25

after dinner" on the y-axis. We calculated a linear correlation coefficient

00:30

of r = -0.27. This coefficient shows a relationship of... what?

00:37

And here are the potential answers...

00:42

All we have to do is interpret the r-value to figure out whether or not the hypothesis is true.

00:48

Remember that r is the correlation coefficient of a set of data.

00:52

In other words, it tells us how good of an approximation we have.

00:57

In this case, we have a linear approximation, so r tells us how close to a line the data forms.

01:04

R values range between -1 and 1. The closer

01:08

r is to 0, the worse our approximation. However, as r approaches either end of its range, the

01:14

better the approximation. How can the correlation get better by moving

01:18

in either direction? Well, the more negative r is, the better a

01:21

negative correlation we have. The more positive, the better the positive correlation.

01:26

But what does THAT mean?

01:28

A positive correlation means that the data has a positive linear

01:32

slope, and a negative correlation means it has a negative linear slope.

01:36

We have an r value of -.27, which means there is a negative correlation.

01:42

Just from this knowledge, we can eliminate (A), (B), and (E).

01:46

-.27 is closer to 0 than -1. In other words, it's closer to having no correlation

01:52

than having a perfect correlation. Which means that the correlation is pretty weak.

01:56

Since we have a weak negative correlation,

01:58

our answer is (C). Even though the correlation is weak, there

02:01

is definitely a negative correlation... ...which means that the more Hulu you watch,

02:06

the less homework you'll get done.

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