Transcript Introduction to Statistics

AP Statistics:
Introduction
What is Statistics?
 Statistics
is the science (and art) of
learning from data.
 It includes:
1.
2.
3.
4.
A
Analyzing Data
Producing Data
Probability
Inference
statistically literate person will begin
his/her examination of a set of data with
the following questions:
Who?
 What
individuals (people/animals/things*)
are being described by the data?
 How many individuals are being studied?
What?
 What
variables (characteristics of individuals)
are being described by the data?
 How many variables are there?
 What kind of variables are being studied?
 Categorical –places individuals into one of
several groups or categories.

Quantitative – takes numerical values for
which arithmetic operations such as adding
and averaging make sense.
 NOT ALL NUMERICAL DATA IS
QUANTITATIVE!!!!!
Why?
 Why
were the data gathered?
 Beware of BIAS!
How?
 There
are 2 different types of statistical
studies…
Distracted Driving Experiment
Research from the University of Utah
Video: The New York Times Distracted
Driving
Experiment: Deliberately imposes some
treatment on individuals to observe their
responses
What is the role of statistics?
 To
pass laws against cell phone use in
cars, evidence must be produced which
proves cell phones are detrimental to
safety
 It
is not enough to infer from convenient
observations that it “seems like people on
cell phones are more distracted than
other drivers”
Tanning Beds and Cancer Research
 ABC
reports on American Cancer Society
findings
 Observational
Study: observes individuals
and measures variables of interest but
does not attempt to influence the
response.
 Also
includes surveys
Which type of study is better?
 An
experiment is better because it
enables the researcher to control for
some of the confounding variables.
 If we simply observe drivers who get in
accidents when they are on their cell
phones, what variables might get in
the way?
 Weather, type of road, how many
people are in the car, type of car
Why don’t we always do experiments?
 Tanning
study….can we assign
people to use a tanning bed a
certain # of times a week?
 External Validity (the extend to
which we can apply our results to
the outside world) is also an issue.
 Milgram
Experiment
Gallup Polls
 Regularly
conducts public opinion
polls in more than 140 countries
 Reliable data since survey methods
involve random sampling and
careful wording of questions
 www.gallup.com
Population vs. Sample
 Population:
the entire group of individuals
that we want information about
 Sample: the part of the population that
we will actually examine in order to
gather information
 Find an interesting Gallup Poll and
determine the sample and the population
AP Statistics Data Collection
 https://spreadsheets.google.com/viewfor
m?formkey=dGFxc3RnTmpVeXFfMDRJMlh
RM0xLenc6MQ
 Visit my Web Page to find the link