QA 233 (Basic Business Statistics)
Solutions to Practice Problem Set I
Suppose
that the manager of a fast food restaurant has collected the following data from
fifty-three randomly selected customers: Size of Soft-Drink Ordered (small,
medium, or large), Method of Payment (cash, check, money order, etc.),
Size of Check (i.e., Amount Spent on Food), Size of Tip, Time Spent
Waiting to Order, and Number of Diners on the Check.
-
Has
the manager collected a census or a sample? Please explain.
The
manager has collected a sample.
The manager has taken data from a subset of his population.
-
How
many observations has the manager collected?
The
manager has collected fifty-three
observations.
-
On
how many variables has the manager collected data?
The
manager has collected data on six
variables: Size of Soft-Drink Ordered,
Method of Payment, Size of Check, Size
of Tip, Time Spent Waiting to Order, and Number
of Diners on the Check.
-
At
what level is each variable measured? What are the ramifications (i.e.,
how does this limit what you can do analytically with each variable)?
Size
of Soft-Drink Ordered:
Ordinal (difficult to discern from nominal in this case)
Method
of Payment:
Nominal
Size
of Check:
Ratio
Size
of Tip:
Ratio
Time
Spent Waiting to Order:
Ratio
Number
of Diners on the Check:
Ratio
We
can calculate a variety of statistics (such as the mean) for any variable
measured quantitatively (i.e., on either the interval or ratio scale). For
any qualitatively measured (i.e. on either the nominal or ordinal scale),
all we can do is count the number of observations in a particular group (and
use this information to calculate a proportion).
-
Is
this data time-series or cross-sectional in nature? Why?
The
data is cross-sectional in nature. A single observation has been made
at a single point in time for each entity included in the sample.
-
Have
these data been collected observationally or experimentally? Explain why?
The
data have been collected observationally.
There is no indication that any attempt has been made to control the
conditions under which the data are collected.
-
From
what population has this data been collected?
The
manager has taken a sample from a subset of all customers of his fast
food restaurant.
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