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 DrinksBrewed 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 studyWe 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, 7:30- 9:30 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 AssociationTest 1
Kids Tall Grande Venti0
10
20
30
40
50
60
MaleFemale
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 AssumptionsState
• 2 independent SRS• All expected counts
are greater than or equal to 5
Check
• 2 independent SRS- assumed
• This condition was not met however we proceeded with the test
Chi- Square Test for Association:
Gender vs. Drink SizeHo: There is no association between gender and drink size
Ha: There is an association between gender and drink
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.
9216.3...865.43
)865.4349(
5855.1
)5855.11()( 2222
Exp
ExpObs
27.3|9216.32 dfP
Chi- Square for Association Test 2
Kids Tall Grande Venti0
5
10
15
20
25
30
35
40
45
50
CoffeeEspressoFrappacinoTeaClassic Favs
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
2295.12|2223.152 dfP
2223.15...3918.1
)3918.12(
88144.0
)88144.01()( 2222
Exp
ExpObs
Ho: There is no association between drink size and drink selectionHa: There is an association between drink size and drink selection
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
Coffe
e
Espre
sso
Frappac
ino
Tea
Classi
c Fav
other
0
10
20
30
40
50
60
MaleFemale
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
State2 Independent SRS
CheckAssumed
.1563 x 128 = 20
.8437 x 128 = 108
.3458 x 107= 37
.6542 x 107 = 70
Pop > 1,280Pop > 1,070mm
ff
mm
mm
ff
ff
npop
npop
pn
pn
pn
pn
10
10
)1(
)1(
10
10
2-Proportion Z-Test: Gender and Drink Selection
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.
4106788.3)3759.3(
3759.311
)ˆ1(ˆ
ˆˆ
:
:
zP
nnpp
ppz
ppHa
ppHo
mf
mf
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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
ConclusionBased 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.