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

MondayDoylestown N Main Street, 7-

9 pm WednesdayDoylestown Main Street, 7:30-

9:30 am FridayWarrington 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

Coffee

Espresso

Frappac

inoTea

Classic

Favoth

er0

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

npoppnpn

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

mf

mf

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 thanwomen. However, the category of Espresso ismost popular. The choice of men's drink size

wastypically smaller, whereas women's selection

was more equally distributed.