Part I Yippee! I’m in Statistics Chapter 1 Statistics or Sadistics?: It’s Up to You

Why Statistics?  Statistics for People Who (Think They) Hate Statistics Follows an approach that is:  Un-intimidating  Informative  Applied  Even a little fun!

A Five-Minute History  17 th century the first set of data pertaining to populations was collected  Need arose to develop specific tools to help answer specific questions  Basic statistical procedures were developed in the fields of Agriculture Astronomy Politics

Statistics: What It Is (and Isn’t)  Statistics describes “a set of tools and techniques that is used for describing, organizing, and interpreting data.”  The text will help you learn how to do the following with data: Collect Organize Summarize Interpret

Descriptive or Inferential?  What is Descriptive Statistics? Used to organize and describe the characteristics of a particular data set  Example: the average age of everyone in this class!  What is Inferential Statistics? Used to make inferences from your “sample” to the “population”  Example: comparing the mean age of students taking this course to average age of all students in an introductory statistics course

Why Statistics is Important  Understanding basic statistics will help you in the following ways: Better prepare you for advance courses (both undergraduate or graduate) Sets you apart from those who do not take courses in statistics Challenges you intellectually Makes you a better student in the behavioral or social sciences!!

Success in this Course  A few hints for successful completion of this course You’re not dumb How do you know statistics is hard? Don’t skip lessons!! Form a study group Ask questions Work through the exercises in each chapter Practice, Practice, Practice Look for real-world applications Browse HAVE FUN!!

About Those Icons

Key to Difficulty Index  VERY Hard  Hard  Not too hard, but not too easy  Easy  VERY Easy

Glossary Terms to Know  Descriptive statistics Data or data set  Inferential statistics Population Sample

Algebraic Order  Parentheses and Brackets -- Simplify the inside of parentheses and brackets before you deal with the exponent (if any) of the set of parentheses or remove the parentheses.  Exponents -- Simplify the exponent of a number or of a set of parentheses before you multiply, divide, add, or subtract it.  Multiplication and Division -- Simplify multiplication and division in the order that they appear from left to right.  Addition and Subtraction -- Simplify addition and subtraction in the order that they appear from left to right.

PEMDAS  Important: It is not correct to say that we must always do addition before subtraction, because A comes before S in PEMDAS  For example: We get 8 working left to right  Another example: 5 x 6 ÷ 2 ÷ 5. We get 3 working left to right.

Now You Try!  2+5*X  2+(3-1) * 3 2  5- (10) 2 /50  Sqrt [ 5(8) – (4) 2 ] [ 3(6) –(3) 2 ]

Chapter 114 Learning a new language Types of variables  How it can be measured matters Discrete variables  What is measured belongs to unique and separate categories Pets: dog, cat, goldfish, rats  If there are only two categories, then it is called a dichotomous variable Open or closed; male or female

Chapter 115 Learning a new language Types of variables Continuous variables  What is measured varies along a line scale and can have small or large units of measure Length Temperature Age Distance Time

Chapter 116 Learning a new language Measurement scales: Nominal  Measurement scales Nominal scales  Separated into different categories  All categories are equal Cats, dogs, rats NOT: 1 st, 2 nd, 3 rd  There is no magnitude within a category One dog is not more dog than another.

Chapter 117 Learning a new language Measurement scales: Nominal  No intermittent categories No dog/cat or cat/fish categories  Membership in only one category, not both  Mutually exclusive properties

Chapter 118 Learning a new language Measurement scales: Ordinal Ordinal scales  What is measured is placed in groups by a ranking 1 st, 2 nd, 3 rd

Chapter 119 Learning a new language Measurement scales: Ordinal  Although there is a ranking difference between the groups, the actual difference between the group may vary. Marathon runners classified by finish order  The times for each group will be different  Top ten 4- to 5-hour times  Bottom ten 4- to 5-week times 1 st place2 nd place3 rd place Time

Chapter 120 Learning a new language Measurement scales: Interval Interval scales  Someone or thing is measured on a scale in which interpretations can be made by knowing the resulting measure.  The difference between units of measure is consistent. Height Speed Length

Chapter 121 Learning a new language Measurement scales Ratio scale  Just like an interval scale, and there is a definable and reasonable zero point. Time, weight, length  Seldom used in social sciences  All ratio scales are also interval scales, but not all interval scales are ratio scales