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Sampling and Experimentation Videos 2 videos

AP Statistics 1.1 Sampling and Experimentation
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AP Statistics: Sampling and Experimentation Drill 1, Problem 1. Which of the following statements is true?

AP Statistics 1.2 Sampling and Experimentation
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AP Statistics: Sampling and Experimentation Drill 1, Problem 2. Which of the following studies would be the best approach to finding his new l...

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AP Statistics 1.1 Sampling and Experimentation 248 Views


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AP Statistics: Sampling and Experimentation Drill 1, Problem 1. Which of the following statements is true?

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Transcript

00:03

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

00:06

They're loud... but fortunately not as loud as polka itself.

00:10

Samantha notices that every time she wears her red polka-dot shirt, she does better on her tests.

00:15

For a year, she records her test grades and which shirt she is wearing during the test.

00:20

She finds that when she wears her red polka-dot shirt, her scores are on average 15% higher

00:26

than when she wears any other top. Which of the following statements is true?

00:31

And here are the potential answers...

00:35

So Samantha has conducted an experiment to try and figure out

00:38

whether her polka-dotted shirt is lucky or not.

00:41

She's noticed that her test scores are 15%

00:44

higher when she wears it... ...and we have to figure out which of the

00:47

three statements given are true.

00:50

The first one says that wearing the red polka-dot

00:52

shirt causes Samantha to receive higher test scores.

00:56

This implies a cause and effect relationship between her clothing and her test scores.

01:00

In other words, her shirt directly affects her scores.

01:03

This seems unlikely, as shirts are not generally known to affect testing capability...

01:08

Simply because Samantha's scores increase when she wears her red shirt doesn't mean

01:13

one causes the other.

01:15

Answer A just isn't true.

01:16

So we move onto the second statement, which

01:18

suggests correlation between the two events.

01:21

Correlation simply means that there is a connection between two events.

01:25

If Samantha wears her shirt, then her score increases 15%.

01:30

If..., then...This relationship suggests correlation...just

01:34

the fact that there IS a relationship.

01:36

Moving onto statement 3.

01:38

The simple fact that Samantha is aware of her experimental condition... means that she

01:42

could be inducing a bias in her test scores. If she believes that her red shirt helps her

01:48

do better, this psychological boost could be the real reason her scores increased by

01:52

15%. This unreal belief that causes a real effect

01:56

is called the placebo effect. So only statements 2 and 3 are right.

02:00

The answer is (E). So, unfortunately for Samantha's shirt, it

02:04

seems as if it may not be too responsible for all of her success.

02:08

Maybe they can still be friends.

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