Lecture 1. 1. STOR . 155 Introductory Statistics. Lecture 1: Overview. The. UNIVERSITY . of. NORTH CAROLINA. at. CHAPEL HILL. 8/25/2009. Lecture 1. 2. Registration Issues. Contact . Charlotte . Rogers. ID: 595618 Download Presentation

Lecture 1. 1. STOR . 155 Introductory Statistics. Lecture 1: Overview. The. UNIVERSITY . of. NORTH CAROLINA. at. CHAPEL HILL. 8/25/2009. Lecture 1. 2. Registration Issues. Contact . Charlotte . Rogers.

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8/25/2009

Lecture 1

1

STOR 155 Introductory Statistics

Lecture 1: Overview

The

UNIVERSITY

of

NORTH CAROLINA

at

CHAPEL HILL

Slide28/25/2009

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.

Slide38/25/2009

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

Slide48/25/2009

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

Slide58/25/2009

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

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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.

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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.

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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

…

…

…

…

…

Slide98/25/2009

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?

Slide108/25/2009

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.

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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.

Slide128/25/2009

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

Slide138/25/2009

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 ?

Slide14Take 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 …

8/25/2009

Lecture 1

14

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