Stor 155 introductory statistics
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The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL. STOR 155 Introductory Statistics. Lecture 1: Overview. Registration Issues. Contact Charlotte Rogers : Hanes 321, 962-2307, [email protected] Fill out some paperwork with her to be put on the waiting list.

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Stor 155 introductory statistics



STOR 155 Introductory Statistics

Lecture 1: Overview

Lecture 1

Registration issues
Registration Issues

  • Contact Charlotte Rogers:

    Hanes 321, 962-2307,

    [email protected]

  • Fill out some paperwork with her to be put on the waiting list.

Lecture 1

My strategy for success
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

Lecture 1

What is statistics
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."


    Introductory Statistics

Lecture 1

What is statistics1


Inference about population (using statistical tools)

Sample of data

What is Statistics?

  • Statistics: the science of collecting, organizing, and interpreting data.

  • data = information

Lecture 1

How can statistics help us
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.

Lecture 1

Sat scores
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.

Lecture 1

Sat scores1
SAT Scores

  • After nine months, all students were given the same standardized tests: the verbal test and the mathematics test.

Lecture 1

Sat scores2
SAT Scores

  • This example involves data collection, data analysis,andstatistical 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?

Lecture 1

Fundamental concepts
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.

Lecture 1

Fundamental concepts1
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.

    • asample analogy of the parameter.

Lecture 1

Practice exercise
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

Lecture 1

Take home message
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 statistics … what ?

Lecture 1

Take home message1
Take home message

  • Interested in population, but it’s too large to become known completely

  • Statisticians 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 …

Lecture 1