Part IYippee! 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 17th 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:  4 - 1 + 7 - 2.  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) * 32

5- (10)2 /50 Sqrt [ 5(8) – (4)2 ] [ 3(6) –(3)2 ]

Chapter 1 14

Learning a new languageTypes 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 1 15

Learning a new languageTypes 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 1 16

Learning a new languageMeasurement scales: Nominal

Measurement scales Nominal scales

Separated into different categories All categories are equal

Cats, dogs, rats NOT: 1st, 2nd, 3rd

There is no magnitude within a category One dog is not more dog than another.

Chapter 1 17

Learning a new languageMeasurement scales: Nominal

No intermittent categories No dog/cat or cat/fish categories

Membership in only one category, not both Mutually exclusive properties

Chapter 1 18

Learning a new languageMeasurement scales: Ordinal

Ordinal scales What is measured is placed in groups by a ranking

1st, 2nd, 3rd

Chapter 1 19

Learning a new languageMeasurement 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

1st place 2nd place 3rd place

Time

Chapter 1 20

Learning a new languageMeasurement 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 1 21

Learning a new languageMeasurement 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

0 +10 +20-20 -10