ShmoopTube

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

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

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

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

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

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

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And here are the potential answers...

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So Samantha has conducted an experiment to try and figure out

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whether her polka-dotted shirt is lucky or not.

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She's noticed that her test scores are 15%

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

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three statements given are true.

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The first one says that wearing the red polka-dot

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shirt causes Samantha to receive higher test scores.

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

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In other words, her shirt directly affects her scores.

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

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

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one causes the other.

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Answer A just isn't true.

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So we move onto the second statement, which

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suggests correlation between the two events.

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

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

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

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the fact that there IS a relationship.

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Moving onto statement 3.

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

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

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

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15%. This unreal belief that causes a real effect

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

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

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

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Maybe they can still be friends.

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