What is Statistics?
Why Study Statistics?
Key Concepts of Statistics
Introducing the Basic Words of the Survey
What is the Discipline of Statistics?
Stats as a Discipline
Type of Mathematics
How different?
Most important element?
• The art and science of
collecting, analyzing,
presenting, interpreting
and distilling data
• Applied mathematics,
different from all other
math courses you’ve ever
taken
• It’s ‘chatty’math,
imprecise and subject to
interpretation.
• Statistics is about
common sense
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2 Dictionary Meanings for the Word
‘Statistics’
1. A set of numerical facts
2 The method used to collect, analyze, present, interpret
and distill data to make intelligent decisions
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How Can Statistics Help Us?
Stats help us make scientific
and intelligent decisions,
often called educated guesses about real
life phenomena
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What happens without Statistics?
Without stats we live in
uncertainty with no
precise solutions to real-life problems.
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Key Vocabulary in Surveys
• _______Statistical surveys usually
begin with a general idea
we want an answer for
• _______The entire collection of
individuals or objects about
which information is desired
• _______A subset of the population
selected for a study by some
specific criteria or in a prescribed
manner. Usually chosen randomly.
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Key Vocabulary Continued
• ________
• ________
• ________
A study using the entire
population
An object which is one
member of the sample. The
member could be a person,
animal or thing
Any characteristic of an
individual. These characteristics
take on different values for
different individuals.
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Key Vocabulary Continued
• _______
• _______
• ________
• ________
A voluntary encounter between
strangers, one the interviewer
and the other the individual.
A person who seeks
information from the individual
by engaging in a special type of
conversation.
Numbers collected in a particular
context. During a survey, the
interviewer collects this. Almost
always has units.
The person who analyzes, distills
and interprets the data collected.
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Key Vocabulary Continued
• _________
• _________
Take the data.
Crunch it. Interpret it in context.
Take the conclusions and decide
if they apply to the sample only
or to the larger population.
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Key Vocabulary Continued
• Here are three terms:
Individual, Sample and
Population. Generally
speaking, in set theory
terms, for a survey,
Normal Survey
Individual
Sample
individual sample population
Population
Census
If however,
all individuals = sample = population,
then you have a census.
Individual
Individual
All Individuals=
Sample = Population
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Good Data vs. Bad Data
Good Data
Bad Data
The result of intelligent
effort and good random
sampling methods
The result of laziness, lack
of understanding, bad
sampling technique or the
desire to mislead others
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Applying Statistical Vocabulary--Example
• Question
Why gather
the data?
• Survey
Is achievement at Washington
High School different for males
vs. females?
We want to know if
Washington HS gender
population has different
achievement, so we
design a survey to answer the
question.
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Applying Statistical Vocabulary—Cont’d
• Population
Begin by using
WHS as our population to study
• Pop vs. Sample Do we have to use the
whole population of WHS or can
we sample them?
• Sample Size If a sample, then how many
individuals should we choose &
how should we choose them?
We decide on 200 students, 100
males and 100 females, 50 from
each of the freshmen, sophomores,
juniors and seniors.
• How to Sample? We will RANDOMLY choose
individuals
in each category
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Applying Statistical Vocabulary—Cont’d
• Individuals
Randomly select 25-25-25-25
males by class and 25-25-25-25
females by class in the school
• Variable
What data will we collect?
Decide on “What is your GPA?”-as a measure of achievement
• Data
Collect it by interview or by
looking at ‘office data.’ Collect
GPA numbers for our 4 levels of
males vs. 4 levels of females.
• Units of Data The unit of GPA is a number
between zero and four in points.
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Applying Statistical Vocabulary—Cont’d
• Analysis
Compare the ‘average’ GPA’s for
males vs. females for each grade
level at WHS, using our collected
data. Compare overall GPA’s, too.
• Conclusion
1) GPA’s are the similar for
males and females
2) GPA’s are higher for males vs. females;
3) GPA’s are higher for females vs. males
Possibilities
• Applicability
Are our conclusions true for the
entire population of WHS?
Or for all American high school
students?
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Elements of a Survey
1 What question is to be answered?
2 Why specifically are we gathering the
data? (What do we want to know?)
3 What population is going to be used to
answer the question?
4 What sample of the population
represents the whole?
5 How is the sample chosen?
6 Is the sample random?
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Elements of a Survey
7 How many individuals in the sample are
chosen and in what units?
8 What is the variable to be measured and
what data represents that variable?
9 What are the units for each piece of data
collected?
10 Any question about the trustworthiness
of the data?
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Elements of a Survey
11 What are some general conclusions to
be drawn about the results?
12 Can we apply the conclusions to the
entire population? Can we apply the
conclusion beyond the population?
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CW 100—Fast
Food & USA
Today
7 How were the individuals chosen? Was the sample random?
8 What was the variable? (What characteristic was measured?)
1 What question was trying to be answered? (by implication)
9 What were the units of the variable?
2 Why specifically were the data gathered?
10 Any question about the trustworthiness of the data? Describe in
a full sentence.
3 What population was the focus? (by implication)
4 Was the survey a census or a sample?
5 How do you know your answer to #4 is correct? (full sentence)
11 Who analyzed the data?
12 What are at least 2 conclusions YOU can draw from the results?
(full sentences)
6 Describe the sample: including units, numbers, conditions.
A
B
13 Can you apply these conclusions to the whole population? Why
or why not? (full sentence)
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Key Vocabulary in Statistics--Answers
• Question
• Population
• Sample
Statistical surveys usually
begin with a general idea
we want an answer for
The entire collection of
individuals or objects about
which information is desired
A subset of the population
selected for a study by some
specific criteria or in a prescribed
manner
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Key Vocabulary Continued--Answers
• Census
• Individual
• Variable
A study using the entire
population
An object which is one
member of the sample. The
member could be a person,
animal or thing
Any characteristic of an
individual. These characteristics
take on different values for
different individuals.
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Key Vocabulary Continued--Answers
• Survey
• Interviewer
• Data
• Statistician
A voluntary encounter between
strangers, one the interviewer
and the other the individual.
A person who seeks
information from the respondent
by engaging in a special type of
conversation.
Numbers collected in a particular
context. During a survey, the
interviewer collects this. Always
has units.
The person who analyzes, distills
and interprets the data collected.
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Key Vocabulary Continued--Answers
• Analysis
• Applicability
Take the data.
Crunch it. Interpret it in context.
Take the conclusions and decide
if they apply to the sample only
or to the larger population.
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The 4-Tardy Rule
•
•
•
•
DON’T BE TARDY TO CLASS!
On your 3rd tardy to class during a semester I
will remind you that you have reached my limit.
On your 4th tardy to class, I will deduct 2 points
from your next test.
On each succeeding tardy after that, you will
also lose another 2 points.
Lost points can make a HUGE difference in your
grade. . .
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