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AP Statistics Videos 40 videos

AP Statistics 2.1 Exploring Data
210 Views

AP Statistics 2.1 Exploring Data. How does this change affect the mean, standard deviation, and IQR?

AP Statistics 5.1 Exploring Data
37 Views

AP Statistics 5.1 Exploring Data. What does this information tell us about the data?

AP Statistics 5.2 Exploring Data
23 Views

AP Statistics 5.2 Exploring Data. Which method would not be a good option?

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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?

Language:
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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