Introduction to Business Research Method

1. Lecture 1
by Selim Bora
Business Research Methods

2. Individuals and Variables
 Individuals are the objects described a set of
data. Individuals may be people, but they may
also be animals or things.
 A variable is any characteristic of an individual. A
variable can take different values for different
individuals.
 Some variables, such as age and income, take
numerical values.

3. Observational Studies
 An observational study observes individuals and
measures variables of interest but does not
attempt to influence the responses.
 A response is a variable that measures an
outcome or result of a study.
 The purpose of an observational study is to
describe some group or siuation.

4. Sample Surveys
 Sample surveys survey some group of individuals by
studying only some of its members, selected not
because they are of special interest but because they
represent the larger group.
 The population in a statistical study is the entire group
of individuals about which we want information.
 A sample is the part of the population from which we
actually collect information and is used to draw
conclusions about the whole.
 A census is a sample survey that attempts to include
the entire population in the sample.

5. Experiments
 An experiment deliberately imposes some
treatment on individuals in order to observe their
responses. The purpose of an experiment is to
study whether the treatment causes a change in
the response.
 The goal of an experiment is usually to learn
whether some treatment actually causes a certain
response.

6. Biased Sampling Methods
 The design of a statistical study is biased if it
systematically favors certain outcomes.
 Selection of whichever individuals are easiest to
reach is called convenience sampling.
 A voluntary response sample chooses itself by
responding to a general appeal. Write-in or call-in
opinion polls are examples of voluntary response
samples.
 Convenience samples and voluntary responses are
often biased.

7. Simple Random Samples (SRS)
 The deliberate use of chance in producing data is one
of the biggest ideas of statistics.
 An SRS of size n consists of n individuals from the
population chosen in such a way that every set of n
individuals has an equal chance to be the sample
actually selected.
 A table of random digits is a long string of the digits 0,
1, 2, 3, 4, 5, 6,7, 8, 9 with these two properties:
 Each entry in the table is equally likely to be any of the
10 digits 0 through 9.
 The entries are independent of each other. That is,
knowledge of one part of the table gives no information
about any other part.

8. How to choose an SRS?
 Label. Assign a numerical value to every
individual in the population. Be sure that all labels
have the same number of digits if you plan to use
a table of random digits.
 Software or table. Use random digits to select
labels at random.