Introductory Statistics

592 Pages·2016·12.48 MB·English

INTRODUCTORY
STATISTICS
4th Edition
By OpenStax College
Adapted by Riyanti Boyd & Natalia Casper
Special Acknowledgement to Mark Beintema & Gladys Poma
This page is purposely left blank.
Introductory Statistics
Susan Dean and Barbara Illowsky (Published 2013 by OpenStax College)
Adapted by: College of Lake County Faculty: Riyanti Boyd and Natalia Casper
Revised July 2021
This project was funded by a grant from the College of Lake County Foundation.

Adapted College of Lake County text can be found at:
http://dept.clcillinois.edu/mth/oer/IntroductoryStatistics.pdf

Original text materials for Introductory Statistics by Dean and Illowski 2013
available at: http://cnx.org/content/col11562/latest/.

Original Publication Under the following license:
This work is licensed under the
Creative Commons Attribution-Noncommercial-Share Alike 3.0 unported license.
To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/
or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco,
California, 94105, USA.
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Table of Contents (4th Edition)

Chapter 1 Sampling and Data 1
Section 1.1 Basic Definitions 2
Section 1.2 Data and Sampling 7
Section 1.3 Experimental Design and Ethics 19
Exercises 29
Solutions 38
Chapter 2 Displaying Data 41
Section 2.1 Frequency Distributions 43
Section 2.2 Graphs for Qualitative Data 49
Section 2.3 Graphs for Quantitative Data 55
Exercises 71
Solutions 78
Chapter 3 Numerical Descriptors 83
Section 3.1 Measures of Central Tendency 84
Section 3.2 Measures of Variation 94
Section 3.3 Measures of Relative Position 102
Exercises 119
Solutions 134
Chapter 4 Probability Topics 137
Section 4.1 Terminology 138
Section 4.2 Independent and Mutually Exclusive Events 145
Section 4.3 Two Basic Rules of Probability 153
Section 4.4 Contingency Tables 164
Section 4.5 Counting and Probability 169
Exercises 180
Solutions 202
Chapter 5 Discrete Random Variables 205
Section 5.1 Probability Distribution Function (PDF) for a Discrete 206
Random Variable
Section 5.2 Mean, Expected Value, and Standard Deviation 209
Section 5.3 Binomial Distribution 216
Section 5.4 Geometric Distribution 226
Section 5.5 Poisson Distribution 231
Exercises 241
Solutions 260
Chapter 6 Continuous Random Variables 265
Section 6.1 Continuous Probability Distributions 266
Section 6.2 Uniform Distribution 270
Section 6.3 Exponential Distribution 281
Exercises 294
Solutions 307

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Table of Contents (4th Edition)

Chapter 7 Normal Distribution 313
Section 7.1 Standard Normal Distribution 315
Section 7.2 Using Normal Distribution 322
Exercises 341
Solutions 352
Chapter 8 The Central Limit Theorem 355
Section 8.1 The Central Limit Theorem for Sample Means and Sample 358
Proportions
Section 8.2 Using the Central Limit Theorem 368
Section 8.3 The Central Limit Theorem for Sums 371
Exercises 378
Solutions 389
Chapter 9 Confidence Intervals 391
Section 9.1 Introduction 392
Section 9.2 Confidence Interval for Single Population Mean when σ 396
known
Section 9.3 Confidence Interval for Single Population Mean when σ 406
unknown
Section 9.4 Confidence Interval for Single Population Proportion 413
Section 9.5 Confidence Interval for Standard Deviation, σ (Optional) 420
Exercises 429
Solutions 449
Chapter 10 Hypothesis Testing with One Sample 453
Section 10.1 Elements of a Hypothesis Test 456
Section 10.2 The Z-test for a Single Population Mean using p-value 463
Section 10.3 The T-test for a Single Population Mean using p-value 467
Section 10.4 Hypothesis Test for a Single Population Proportion using 471
p-value
Section 10.5 Critical Values and the Critical Value Method 476
Section 10.6 Type I and Type II Errors 484
Exercises 491
Solutions 508
Chapter 11 Hypothesis Testing with Two Samples 513
Section 11.1 Two Population Means with Known σ and σ 515
1 2
Section 11.2 Two Population Means when σ and σ are Unknown 521
1 2
Section 11.3 Comparing Two Population Proportions 531
Section 11.4 Matched Pairs Test 539
Section 11.5 Confidence Intervals from Two Samples 546
Exercises 555
Solutions 571

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Table of Contents (4th Edition)

Chapter 12 The Chi-Square Distribution Continued 575
Section 12.1 Introduction to Chi-square Distribution 576
Section 12.2 Confidence Intervals for Variance/Standard Deviation 580
Section 12.3 Test of a Single Variance 583
Section 12.4 Goodness of Fit Test 587
Section 12.5 Test of Independence and Test for Homogeneity 596
Exercises 607
Solutions 625
Chapter 13 Linear Regression and Correlation 629
Section 13.1 Linear Equations 630
Section 13.2 Scatter Plots 633
Section 13.3 The Regression Equation 638
Section 13.4 Testing the Significance of the Correlation Coefficient 649
Section 13.5 Prediction 658
Section 13.6 Outliers 660
Section 13.7 Summary of Concepts using TI-83/84 and Excel 666
Exercises 676
Solutions 691
Chapter 14 F Distribution and One-Way ANOVA 695
Section 14.1 Test of Two Variances/Standard Deviations 696
Section 14.2 One-way ANOVA 703
Exercises 712
Solutions 724
Appendix
Standard Normal Table A1
T-distribution Tables B1
Chi-Square Tables C1
r critical value Table D1

This Photo by Unknown Author is licensed under CC BY-

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1 | SAMPLING AND DATA

Figure 1.1 Photo by Markus Spiske on Unsplash
Introduction
Chapter Objectives: By the end of this chapter, the student should be able to
• Understand basic statistical terminology
• Recognize and differentiate between key terms.
• Apply various types of sampling methods to data collection.
You are probably asking yourself the question, "When and where will I use statistics?" If you
read any newspaper, watch television, or use the Internet, you will see statistical
information. There are statistics about crime, sports, education, politics, and real estate.
Typically, when you read a newspaper article or watch a television news program, you are
given sample information. With this information, you may make a decision about the
correctness of a statement, claim, or "fact." Statistical methods can help you make "best
educated guess."

Since you will undoubtedly be given statistical information at some point in your life, you
need to know some techniques for analyzing the information thoughtfully. Think about
buying a house or managing a budget. Think about your chosen profession. Think about the
Covid-19 pandemic. Think about the political elections. As well, the fields of economics,
business, psychology, education, biology, law, computer science, police science, and early
childhood development require at least one course in statistics.

Included in this chapter are some basic ideas and terms used in Statistics. We will learn how
data are gathered and how to distinguish "good" data from "bad."
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1.1 | Basic Definitions

The science of Statistics deals with the collection, analysis, interpretation, and presentation
of data. We see and use data in our everyday lives. There are two basic branches of
Statistics: Descriptive and Inferential.

• Descriptive Statistics involves organizing and summarizing data. Two general
ways to summarize data are with graphs and numerical values, such as an average.
• Inferential Statistics. Involved learning formal methods for drawing conclusions
from data, which we will learn later in the text. Statistical inference uses probability
to determine how confident we can be that our conclusions are correct.

Effective interpretation of data (inference) is based on good procedures for producing data
and thoughtful examination of the data. We will encounter what may seem to be too many
mathematical formulas for interpreting data. The goal of statistics is not to perform
numerous calculations using the formulas, but to gain an understanding of your data. The
calculations can be done using a calculator or a computer; the understanding must come from
you. If you can thoroughly grasp the basics of statistics, you can be more confident in the
decisions you make in life and in your chosen career.

Key Terms

In Statistics, we generally want to study a population. You can think of a population as a
collection of persons, things, or objects under study. For logistical reasons, it is usually not
possible to gain access to all of the information from the entire population. So when want
to study a population, we usually select a sample. The idea of sampling is to select a
portion (or subset) of the larger population and study that portion (the sample) to gain
information about the population. Data are the result of sampling from a population.

https://openclipart.org/detail/216524/many-and-few

Because it takes a lot of time and resources to examine an entire population, sampling is a
very practical technique. If you wished to compute the overall grade point average at your
school, it would make sense to select a sample of students who attend the school. The data
collected from the sample would be the students' grade point averages. In presidential
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elections, samples of between 1,000 and 2,000 prospective voters are used for opinion polls.
The opinion poll is supposed to represent the views of the people in the entire country.
Manufacturers of canned carbonated drinks take samples to determine if a 16 ounce
can contains 16 ounces of carbonated drink.

From the sample data, we can calculate a statistic. A statistic is a number that represents
a property of the sample. For example, if we consider one math class to be a sample of the
population of all math classes, then the average number of points earned by students in that
one math class at the end of the term is an example of a statistic. The statistic is an estimate
of a population parameter. A parameter is a number that represents a property of the
population. Since we considered all math classes to be the population, then the average
number of points earned per student over all the math classes is an example of a parameter.

One of the main concerns in the field of statistics is how accurately a statistic estimates a
parameter. The accuracy really depends on how well the sample represents the
population. The sample must contain the characteristics of the population in order to be
a representative sample. We are interested in both the sample statistic and the population
parameter in inferential statistics. In a later chapter, we will use the sample statistic to test
the validity of the established population parameter.

A variable, denoted by capital letters such as X and Y, is a characteristic of interest for each
person or thing in a population. Variables may be numerical or categorical.

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• Numerical variables take on numerical values with equal units such as weight in
pounds and time in hours.
• Categorical variables place the person or thing into a category.

If we let X equal the number of points earned by one math student at the end of a term,
then X is a numerical variable. If we let Y be a person's party affiliation, then Y is a
categorical variable, and some possible values of Y would be Republican, Democrat, and
Independent. Y is a categorical variable. We could do some math with values of X (calculate
the average number of points earned, for example), but it makes no sense to do math with
values of Y (calculating an average party affiliation makes no sense).

The actual values of a variable are called data (a single value is a datum); these values
may be numbers or words.

Example 1.1
Determine what the key terms refer to in the following study: We want to know the
average amount of money first-year college students spend at ABC College on school supplies
that do not include books. We randomly survey 100 first-year students at the college. Three
of those students spent $150, $200, and $225, respectively.

Solution 1.1:
The population is all first year students attending ABC College this term.

The sample is the 100 first year students surveyed at the college (although this sample
may not represent the entire population).

The parameter is the average amount of money spent (excluding books) by first year
college students at ABC College this term. This average would be represented by µ.

The statistic is the average amount of money spent (excluding books) by first year college
students in the sample. This average would be represented by .

The variable is the amount of money spent (excluding books) b𝑥𝑥y̅ one first year student.
Let X = the amount of money spent (excluding books) by one first year student attending
ABC College.

The data would be the actual dollar amounts spent by the first-year students. Examples of
the data would be $150, $200, and $225.

1.1 Determine what the key terms refer to in the following study. We want to know the
average amount of money spent on school uniforms each year by families at Knoll Academy.
We randomly survey 100 families with children in the school. Three of the families spent
$65, $75, and $95, respectively.

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