Download Presentation - The PPT/PDF document "8/25/2009" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Presentation on theme: "8/25/2009"— Presentation transcript:
Slide1
8/25/2009
Lecture 1
1
STOR 155 Introductory Statistics
Lecture 1: Overview
The
UNIVERSITY
of
NORTH CAROLINA
at
CHAPEL HILL
Slide2
8/25/2009
Lecture 1
2
Registration Issues
Contact
Charlotte
Rogers
:
Hanes 321, 962-2307,
crogers@email.unc.edu
Fill out some paperwork with her to be put on the waiting list.
Slide3
8/25/2009
Lecture 1
3
My Strategy for Success
Stay active/involved in class.
Ask questions during class (especially if you
do
not understand something).
Do not feel shy or stupid.
Answer questions to help other students if you can.
Keep pace with the lectures, review daily, do homework after each lecture to help understand the materials.
Make effective use of office hours (Instructor and IA) and open tutorial sessions
Help you to answer questions about homework and lectures
Private time vs. public time
Slide4
8/25/2009
Lecture 1
4
What is Statistics?
"Data! Data! Data!" he cried impatiently. "I can't make bricks without clay."
----
Sherlock Holmes
The Adventures of the Copper Beeches
"Data! Data! Data!" he yelled loudly. "I can't teach
Statistics
without
Data
."
----
Instructor
Introductory Statistics
Slide5
8/25/2009
Lecture 1
5
What is Statistics?
Statistics: the science of collecting, organizing, and interpreting data.data = information
Inference about population (using
statistical tools)
Population
Sample of data
Slide6
8/25/2009
Lecture 1
6
How can Statistics help us?
claims that it contains 1000 chips. Is this true?Among a group of randomly chosen people, how likely is it for two of them to have the same birthday?What is the relationship between Income and Years of Education? Design your own experiment, collect data, analyze data and draw conclusions.
Slide7
8/25/2009
Lecture 1
7
SAT Scores
Parents and teachers have been concerned about the trend of declining SAT scores and sought ways to halt the decline.
One question: the effect of
classroom atmosphere
(
strict
or
liberal
).
To answer the question, 50 students (24 males and 26 females) participated in a study on student performance, as measured by SAT scores at the end of the school year.
The students were divided into two groups of 25 each (12 males and 13 females), with Group 1 to study under a
strict
atmosphere while Group 2 under a very
permissive
atmosphere.
They were matched according to socio-economic background.
Slide8
8/25/2009
Lecture 1
8
SAT Scores
After nine months, all students were given the same standardized tests: the verbal test and the mathematics test.
Student
Group
Gender
SATMath
SATVer
A
Strict
F
670
700
B
Strict
M
700
680
C
Liberal
F
750
730
D
Liberal
M
690
750
…
…
…
…
…
Slide9
8/25/2009
Lecture 1
9
SAT Scores
This example involves
data collection
,
data analysis
,
and
statistical inference
.
How?
Questions:
Does stricter classroom atmosphere increase the average score?
Why “matched according to socio-economic background”?
Why “12 males and 13 females per group”?
Is the group size 50 large enough to make a confident conclusion?
Slide10
8/25/2009
Lecture 1
10
Fundamental Concepts
Population
: the entire group of individuals that we want information about.
Students (who are about to take SAT)
Sample
: a part of the population that we actually examine in order to gather information.
those students selected into the study
Sample size
:
number of observations/individuals in a sample.
50
Statistical inference
: to make an inference about a population based on the information contained in a sample.
Based on the data from the study, to infer whether a stricter classroom atmosphere increases SAT scores in general.
Slide11
8/25/2009
Lecture 1
11
Fundamental Concepts
A
parameter
is a value that describes the population. It’s fixed but unknown in practice.
the average SAT score of all the students, who are about to take SAT.
A
statistic
is a value that describes a sample. It’s known once a sample is obtained.
the average SAT score of all the students, who are selected into the study.
a
sample analogy of the parameter.
Slide12
8/25/2009
Lecture 1
12
Practice Exercise
Suppose you are interested in finding out the average SAT score of UNC
unders
,
The SAT scores of all UNC
unders
in
STOR155
The SAT scores of all UNC
unders
Suppose you are interested in finding out the average SAT score of US
unders
,
The SAT scores of all UNC
unders
The SAT scores of all US
unders
Slide13
8/25/2009
Lecture 1
13
Take Home Message
Statistics is the science of
data
:
Collecting
Analyzing
Decision
making
=
Information processing
Fundamental concepts:
Population, parameter,
sample, statistic,
sample
size
You can do a
LOT
with
s
tatistics … what ?
Slide14
Take home message
Interested in population, but it’s too large to become known completelyStatisticians work on sample, which is a smaller and observable ``proxy’’There is uncertainty in this transition, hence errors are inevitable … That’s why statistical methods are needed …
