What would the shape of the distribution of the number of friends be for all Facebook users?

What is your best guess for the average number of friends for all Facebook users?

What does Facebook

claim to be the

average number of

friends?

Is the claim from Facebooksignificantly different from your guess?

How could we determine if Facebook is right or not?

Hypothesis Test

Test whether the average number of friends is more than the Facebook claim with your own data.

H0:

Ha:

Randomly Choose Friends

Randomly Choose Friends

• Math > PRB > randInt(

• randInt(1, [max#friends], [2 to 10])

• Choose friends using random #s and record # of friends these friends have

How many friends do these three friends have? (Submit three separate numbers.)

Compile Data

Add data to L1

Assumptions

State assumptions and describe how each is satisfied.

1. Randomness

2. Normal population distribution

Histogram

2nd > STAT PLOT > ENTER

Highlight On and press ENTER

Type: histogram

xList: L1

Freq: 1

Zoom > 9

What is the shape?

Was your guess close?

Test Results

What is t?

t-Test

Stat > Tests > 2: T-Test…

Use the Data option

Mu0: 130

List: L1

Freq: 1

Mu: >Mu0

Calculate

Test Results

What is t?

What is p?

Test Results

What is t?

What is p?

Can we reject H0 and accept Ha? What is our official conclusion statement, then?

Test Results

What is the average number of Facebookfriends from our sample data?

Is it close to our initial guess?

Is it close to Facebook’sclaim?

What Now?

Should we email Facebook and let them know their stats are wrong?

What Now?

Should we email Facebookand let them know their stats are wrong?

What do they have that we don’t have?

Why might our numbers be different?

What assumptions might be erroneous in our sample?

Assumptions

Again, are the necessary assumptions satisfied?

1. Randomness

2. Normal population distribution