Yummm…
Starbucks Coffee
By Nicole Rodi and Brittney Ferrari
About Starbucks
Starbucks Mission: To inspire and nurture the
human spirit— one person, one cup, and one
neighborhood at a time.
Environmental Mission: Starbucks is
committed to a role of environmental
leadership in all facets of our business.
Starbucks Gives: The Starbucks
Foundation, Social Investments, Ethos
Water, Regional and Local Donations
Diversity at Starbucks: Starbucks has made a business out of
human connections, community involvement and the
celebration of cultures.
Starbucks Drinks
Brewed Coffee
• Coffee of the Week
• Pike Place Roast
Espresso
• Latte
• Cappuccinno
• Caramel Macchiato
Frappuccino
• Caramel, Vanilla Bean,
Mocha
Tazo Tea
• Chai Tea Latte
• Hot/Iced Tea
Classic Favorites
• Hot Chocolate
•
•
•
•
Other
Food (Bagel, Scone, Fruit)
Gift Cards
Merchandise (Cups,
Bagged Coffee)
Water
Drink Sizes
Kids = Kids
Tall = Small
Grande = Medium
Venti = Large
Observational study
We wanted to compare the
gender, drink size and drink
selection of people who drink
Starbucks coffee.
The categories we used for
drink selection were identical
to those of Starbucks.
We went to 4 Starbucks:
Montgomery Mall, 6-8 pm
Monday
Doylestown N Main Street, 7-9
pm Wednesday
Doylestown Main Street, 7:309:30 am Friday
Warrington Barn Plaza, 7-9
pm Sunday
We observed every costumer who came in
during the 2 hour interval.
This was the most effective way to randomize
our study
Chi- Square for Association
Test 1
60
50
40
Male
Female
30
20
10
0
Kids
Tall
Grande
Venti
Exploratory Data Analysis
• The men’s drink size selection is right skewed,
indicating that men preferred smaller sizes.
• The smaller drinks of men might be a result of their
desire for a quick “pick me up” rather than a
delicious treat.
• The women’s drink selection is more evenly
distributed, showing that there was no clear
preference in size.
• This even distribution could be due to the fact that
most women choose the drink and size that they are
in the mood for at that moment in time.
Chi –Square Assumptions
State
• 2 independent SRS
• All expected counts
are greater than or
equal to 5
Check
• 2 independent SRSassumed
• This condition was not
met however we
proceeded with the test
Chi- Square Test for
Association:
Gender vs. Drink Size
Ho: There is no association between gender and drink size
Ha: There is an association between gender and drink
 
2

( Obs  Exp )
2

Exp

P 
2

(1  1 . 5855 )
1 . 5855
2

( 49  43 . 865 )
2
 ...  3 . 9216
43 . 865

 3 . 9216 | df  3  . 27
We fail to reject Ho because the P-value of .27 >α= 0.05. There is
sufficient evidence that there is no association between gender
and size of drink.
Chi- Square for Association
Test 2
50
45
40
35
Coffee
Espresso
Frappacino
Tea
Classic Favs
30
25
20
15
10
5
0
Kids
Tall
Grande
Venti
Exploratory Data Analysis
• The espresso category was ordered the most
in every drink size. This is probably because
it has the largest amount of drink options.
• Classic favorites had the least amount of
orders. Probably because people would
rather get coffee at Starbucks.
Chi- Square for Association:
Drink Size vs. Drink Selection
Ho: There is no association between drink size and drink selection
Ha: There is an association between drink size and drink selection
 
2

( Obs  Exp )
2
Exp

P 
2


(1  0 . 88144 )
2

( 2  1 . 3918 )
0 . 88144
2
 ...  15 . 2223
1 . 3918

 15 . 2223 | df  12  . 2295
We fail to reject Ho because the P-value of .27 >α = 0.05. There is
sufficient evidence that there is no association between drink size
and drink selection.
2 Proportion Z- Test:
Gender and Drink Selection
60
50
40
30
20
10
0
Male
Female
Exploratory Data Analysis
• Espressos was ordered the most by both
women and men probably because it had
the largest amount of drink selection.
• There were more females who went to
Starbucks.
2 Proportion Z-Test
Assumptions
State
2 Independent SRS
nf  pf
 10
n f (1  p f )
nm  pm
n m (1  p m )
pop
pop
f
m
 10
Check
Assumed
.1563 x 128 = 20
.8437 x 128 = 108
.3458 x 107= 37
.6542 x 107 = 70
 10 n f
 10 n m
Pop > 1,280
Pop > 1,070
2-Proportion Z-Test:
Gender and Drink Selection
Ho : p f  p m
Ha : p f  p m
z 
pˆ f  pˆ m
 1
1 

pˆ (1  pˆ ) 

n

n
f
m


  3 . 3759
P ( z   3 . 3759 )  3 . 6788  10
4
We reject the Ho because the P-value <α = 0.05. We have sufficient evidence that
the proportion of women who chose coffee is less than the proportion of men who
chose coffee. We believe this is due to the fact that women chose more specialty
drinks such as Lattes.
Lurking Variables
• Time of day- Morning work
rush, lunch rush, dessert
rush
• Price- Specialty drinks are a
lot more expensive
• Flavors- some people might
not like the flavors offered
• Nutritional value of drinks
• We couldn’t hear as well in
some Starbucks because the
music was loud and
costumers ordered too
quietly.
• The Starbucks on North
Main Street has a drive-thru
Personal Comments
• We thought men would
buy plain coffee and
more women would buy
fancier drinks
• We expected more
women than men to
purchase Starbucks
products
• We thought women
would get smaller sizes
because they have less
calories
Conclusion
Based on our observational study we feel that
no more women than men go to Starbucks.
More men ordered regular coffee more than
women. However, the category of Espresso is
most popular. The choice of men's drink size
was
typically smaller, whereas women's selection
was more equally distributed.