Statistics as a set
of mathematically
based tools and
techniques to
transform raw
(unprocessed)
data in to a few
summary
measures that
represent useful
and usable
information to
support effective
decision making
The statistical
analysis in
management
decision making
is performed via
a Management
decision support
system which is
illustrated in
The Language of
Statistics
A number of important
terms, concepts and symbols
are used extensively in
statistics
Random
variable:
Any attribute
of interest on
which data is
collected and
analysed
Data:
The actual
values
(numbers)
or outcomes
recorded on
a random
variable
Information:
The results
of data
processing,
and is
meaningful
Sample:
A fraction or a subset
of a population that
is selected in order to
carry out a survey. In
many cases,
researchers are
compelled to use
sample data instead
of the full population
Sampling unit:
The object being
measured, counted
or observed with
respect to the
random variable
under study
Sample
statistic:
A measure that
describes a
characteristic of
a sample
Population:
The collection of
all possible data
values that exist
for the random
variable under
study
Population parameter:
A measure that
describes a
characteristic
of a population
Components
of Statistics
Descriptive statistics:
condenses sample data into
a few summary descriptive
measures
When large
quantities of data
have been
gathered, there is
a need to organise,
summarise and
extract the
essential
information
contained within
this data for
communication to
management
These
summary
measures
allow a user
to identify
profiles,
patterns,
relationships
and trends
within the
data
Inferential statistics:
generalises sample
findings to the broader
population
Descriptive statistics only
describes the behaviour
of a random variable in a
sample
However,
management is
mainly concerned
about the
behaviour and
characteristics of
random variables
in the population
from which the
sample was drawn
Inferential statistics is that
area of statistics that allows
managers to understand the
population picture of a
random variable based on
the sample evidence
Statistical modelling: builds
models of relationships between
random variables
Constructs equations between
variables that are related to
each other
These equations
(called models)
are then used to
estimate or
predict values of
one of these
variables based on
values of related
variables
Statistical
Applications in
Management
Finance
At a company level,
statistics is used to
assess the validity of
different investment
projects
Is influenced
by four factors:
datatype, data
source, the
method of data
collection, data
preparation
Selection of
Statistical
Method
Depends on
management
problem to be
addressed
and then on
the type of
data available
Data Types &
Measurement
Scales
Measurement
Scales:
The scale
determines the
extent to which the
data can be
manipulated and
also which
statistical methods
are appropriate to
use on the data to
produce valid
statistical results
Nominal data
is associated with
categorical data. If all
the categories of a
qualitative random
variable are of equal
importance, then this
categorical data is
termed
‘nominal-scaled’
gender (1 =
male; 2 =
female)
city of residence
(1 = PTA; 2 =
DBN)
Ordinal data
is also associated
with categorical
data, but has an
implied ranking
between the
different
categories of the
qualitative
random variable
Each consecutive
category possesses
either more or less
than the previous
category of a given
characteristic
Interval data is
associated with
numeric data and
quantitative
random variables
It is generated mainly
from rating scales,
which are used in
survey
questionnaires to
measure respondents’
attitudes
Ratio data
Ratio data
consists of all
real numbers
associated
with
quantitative
random
variables
employee
ages (years),
customer
income (R),
distance
travelled
(km)
Ratio data has all
the properties of
numbers (order,
distance and an
absolute origin of
zero) that allow
such data to be
manipulated using
all arithmetic
operations
Data Types
Qualitative
random
variables
Generate
categorical
(non-numeric)
response data.
The data is
represented by
categories only
gender of a
consumer
an employee’s
highest
qualification
Quantitative
random
variables
Generate numeric
response data.
These are real
numbers that can
be manipulated
using arithmetic
operations (add,
subtract, multiply
and divide)
age of an
employee
machine
downtime
price of a product in
different stores
Discrete data:
is whole
number (or
integer) data
no. of
students in
a class, no
of cars sold
Continuous
data: is any
number that
can occur in
an interval
the time needed
for an assembly
line, the volume
of fuel for a car
Data Sources
Classification
internal
financial
reports;
departmental
records or
reports
external
internet;
media
Primary data is
data that is
recorded for the
first time at
source and with
a specific
purpose in mind
advantage of
primary-sourced
data is its high
quality
disadvantage of
primary-sourced
data is that it can be
time consuming and
expensive to collect
Secondary data
is data that
already exists
in a processed
format
advantages. First, its
access time is
relatively short
(especially if the data
is accessible through
the internet), and
second it is generally
less expensive
disadvantages are
that the data may
not be problem
specific (i.e. problem
of its relevancy), it
may be out of date
Data
Collection
Methods
Observation
Primary data can be collected by observing
a respondent or a process in action
Advantage: the respondent is unaware of being observed
and therefore behaves more naturally or spontaneously
Disadvantage: the passive form of data collection.
There is no opportunity to probe for reasons or
to further investigate underlying causes
Surveys
The direct questioning of respondents using
questionnaires to structure and record the data collection
Advantages: a higher response rate is generally achieved. it allows
probing for reasons. the data is current and generally more accurate
Disadvantages: personal interviews are:
time consuming. expensive to conduct
Telephone
interviews
Advantages: cost is relatively low. questions
can be clarified by the interviewer
Disadvantage: loss of respondent anonymity
Experimentation
the analyst
manipulates
certain variables
under controlled
conditions
Advantage:
high
quality
Disadvantage
costly and
time-consuming
E-survey
Is geographically dispersed
and it is not practical to
conduct personal interviews
Advantages: Interviewer bias is eliminated.
anonymity of each respondent is assured