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Basic Issues in Statistics
Kazeem Adepoju, PhD
School of Statistics
June 10, 2019
• Definition of Statistics
• How Statistics Helps Us Learn about the
-Practical Questions
-Its Importance, essentials and Procedure
• How Inferences Are Made
• Theory and Reality
What is Statistics?
• Statistics is the art and science of designing
studies and analyzing the data that those
studies produce.
• Its ultimate goal is translating data into
knowledge and understanding of the world
around us.
• In short, statistics is the art and science of
learning from data .
Practical Questions
• How can you evaluate evidence about global
• Are cell phones dangerous to your health?
• What’s the chance your tax return will be audited?
• How likely are you to win the lottery?
• Is there bias against women in appointing
• How can you analyze whether a diet really works?
• How can you predict the selling price of a house?
• Making Conclusions in Medical Research
• Predicting an Election Using an Exit Poll
• Consumers are sampled to provide
information for predicting product
• Using a Survey to Investigate People’s
• controlled environmental conditions on
humans in order to infer the appropriate
treatment for various illnesses.
• Engineers sample a product quality
characteristic and various
Decision Under Uncertainty
• You’ll face financial decisions such as
choosing between an investment with a sure
return and one that could make you more
money but could possibly cost you your entire
Statistics Essentials
• You’ll learn how to analyze the available
information to answer necessary questions
in such scenarios.
• Understanding of statistics is essential for
making good decisions in an uncertain
Statistical Procedure
• Statistical methods help us investigate
questions in an objective manner.
(1)formulate a statistical question
(2)collect data
(3) analyze data
(4) interpret results
How Inferences Are Made
• Why is probability relevant to inferential
statistics? Statistics are, in one sense, all
about probabilities. Inferential statistics
deal with establishing whether differences
or associations exist between sets of data.
The data comes from the sample we use,
and the sample is taken from a population.
How Inferences Are Made
• Suppose that two candidates are running for a
public office in our community and that we
wish to determine whether our candidate,
Jones, is favored to win. The population of
interest is the set of responses from all
eligible voters who will vote on election day,
and we wish to determine whether the fraction
favoring Jones exceeds .5.
Elements of Science
• 1. Reality: the real-world as it exists
independently of human knowledge;
• 2. Theory: coherent sets of ideas about how
some portion of reality works;
• 3. Data: observations and measurements on
some real-world system;
• 4. Models: abstract, but rigorous and specific,
representations of reality, based on theory or
data or both
Theory and Reality
• Theory: A collection of propositions to
illustrate the principles of a subject.
• In modern science, the term "theory"
refers to scientific theories, a wellconfirmed type of explanation of nature,
made in a way consistent with scientific
method, and fulfilling the criteria required
by modern science.
• Scientific theories are the most reliable,
rigorous, and comprehensive form of
scientific knowledge.
• Theories are analytical tools
for understanding, explaining, and
making predictions about a given subject
Illustrative Example
• For each of the following situations,
identify the population of interest, the
inferential objective, and how you might go
about collecting a sample.
(1) A university researcher wants to estimate
the proportion of U.S. citizens from
“Generation X” who are interested in starting
their own businesses.
Illustrative Example
(2)A city engineer wants to estimate the
average weekly water consumption for
single-family dwelling units in the city.
(3) A political scientist wants to determine
whether a majority of adult residents of a
state favor a unicameral legislature.
• Descriptive and Inferential Statistics