OVER OVER BOOKED?BOOKED?A FACEBOOK EXPERIMENTA FACEBOOK EXPERIMENT

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To test the claim that the average teenager

uses Facebook for only 5 hours a week5 hours a week

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•100 subjects

out of 594

friends

• Standardized

Question

• Own Facebook

account used

• Number Assignment + Random Digit Table = SRS

Facebook Empirical Data1 10 14 17 21 26 30 304 11 15 17 21 27 30 304 11 15 17 22 27 30 305 12 15 17 22 27 30 305 12 15 18 22 28 30 305 12 15 18 23 28 30 306 12 15 18 24 29 30 3010 12 15 19 24 29 30 3010 13 15 20 24 29 30 3510 14 15 20 24 29 3010 14 16 20 25 29 3010 14 16 20 25 29 3010 14 16 20 25 30 30

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•Empirical data is translated into appropriate graphical displays.

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Facebook.com claims that the average teenager spends five hours a week using Facebook. [Using Facebook means

actually using its features and not just having it open]. I believe that a teenager uses Facebook for longer than five

hours a week.

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𝐻𝑜: μ = 5 hours A teenager uses Facebook an average of 5 hours a week

𝐻𝑎: μ > 5 hours A teenager uses Facebook for longer than 5 hours a week

n = 100 ∝ = 5%

A One Sample Mean T-Test…because the population standard deviation is unknown standard deviation is unknown &

a mean ≠ proportionmean ≠ proportion

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Conditions:•The distribution is an SRSSRS

•Due to the Central Limit Theorem (CLT) the population is normal since

n>40n>40

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𝑡 = 𝑥ҧ− 𝜇𝑠 ξ𝑛ൗ�

𝑡 = 20.23−58.32 ξ100ൗ�

t = 18.3

Using TI-83 T-test: p-value = .00000000007

* Can not sketch critical region/value because p-value is too small

A mean of 20 hours would occur .000007% of the time if the population mean is 5 hours. So we can safely

reject at the 5% significance level. And conclude that a teenager uses Facebook for more than 5 hours

a week!

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𝐻𝑜

I want to estimate the mean time a teenager spends on Facebook a week.

Since we do not know , I will use the one sample t-interval. The data was collected via a random

experiment. Due to the Central Limit Theorem (CLT) the population is normal since n>40n>40

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𝜎

Confidence Interval = 95%

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𝑥ҧ± 𝑡∗ 𝑠ξ𝑛

20± (1.984) 8.32ξ100

= 18.579 to 21.881 hours

I am 95% confident that the mean time a teenager spends on Facebook a week is between 18.579 to

21.881 hours

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Unclear What Type of Usage

InaccurateAnswers

Standardized Question

Strengths & Weaknesses…

Large # of Subjects

Only My FB Friends

Population Mean is National