What Is Stadistic

Chapter 1

McGraw-Hill/Irwin

©The McGraw-Hill Companies, Inc. 2008

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Understand why we study statistics.
Explain what is meant by descriptive
statistics and inferentialstatistics.
Distinguish between a qualitative variable
and a quantitative variable.
Describe how a discrete variable is different
from a continuous variable.
Distinguish among the nominal, ordinal,interval, and ratio levels of measurement.

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Statistics is the science of

collecting, organizing,
presenting, analyzing, and
interpreting numerical data to
assist in making more effectivedecisions.

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Statistical techniques are used
extensively by marketing, accounting,
quality control, consumers,
professional sports people, hospital
administrators, educators, politicians,physicians, etc...

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Descriptive Statistics - methods of organizing,
summarizing, and presenting data in an
informative way.
EXAMPLE 1: A Gallup poll found that 49% of the people in asurvey knew the name of
the first book of the Bible. The statistic 49 describes the number out of every 100
persons who knew the answer.

EXAMPLE 2: According to Consumer Reports, General Electricwashing machine
owners reported 9 problems per 100 machines during 2001. The statistic 9
describes the number of problems out of every 100 machines.

Inferential Statistics: A decision, estimate,prediction, or generalization about a
population, based on a sample.

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A population is a collection of all possible individuals, objects, or
measurements of interest.

A sample is a portion,or part, of the population of interest

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A. Qualitative or Attribute variable - the
characteristic being studied is nonnumeric.
EXAMPLES: Gender, religious affiliation, type of automobileowned, state of birth, eye color are examples.

B. Quantitative variable - information is
reported numerically.
EXAMPLES: balance in your checking account, minutes
remaining in class, or number...