Page 33 - Statistics for Dummies

Chapter 1: Statistics in a Nutshell
When it comes to distributions, you need to know how to decide which dis-
tribution a particular variable has, how to find probabilities for it, and how to
figure out what the long-term average and standard deviation of the outcomes
would be. To get you squared away on these issues, I’ve got three chapters for
you, one dedicated to each distribution: Chapter 8 is all about the binomial,
Chapter 9 handles the normal, and Chapter 10 focuses on the t-distribution.

For those of you taking an introductory statistics course (or any statistics
course, for that matter), you know that one of the most difficult topics to under-
stand is sampling distributions and the Central Limit Theorem (these two things
go hand in hand). Chapter 11 walks you through these topics step by step so
you understand what a sampling distribution is, what it’s used for, and how it
provides the foundation for data analyses like hypothesis tests and confidence
intervals (see the next section for more about analyzing data). When you under-
stand the Central Limit Theorem, it actually helps you solve difficult problems
more easily, and all the keys to this information are there for you in Chapter 11.
Performing Proper Analyses 17
After the data have been collected and described using numbers and pic-
tures, then comes the fun part: navigating through that black box called the
statistical analysis. If the study has been designed properly, the original ques-
tions can be answered using the appropriate analysis — the operative word
here being appropriate.
Many types of analyses exist, and choosing the right analysis for the right situ-
ation is critical, as is interpreting results properly, being knowledgeable of the
limitations, and being able to evaluate others’ choice of analyses and the con-
clusions they make with them.
In this book, you get all the information and tools you need to analyze data
using the most common methods in introductory statistics: confidence inter-
vals, hypothesis tests, correlation and regression, and the analysis of two-
way tables. This section gives you a basic overview of those methods.
Margin of error and confidence intervals
You often see statistics that try to estimate numbers pertaining to an entire
population; in fact, you see them almost every day in the form of survey
results. The media tells you what the average gas price is in the U.S., how
Americans feel about the job the president is doing, or how many hours
people spend on the Internet each week.

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