Page 26 - Statistics II for Dummies

10 Part I: Tackling Data Analysis and Model-Building Basics

Today, anyone who wants to analyze data can do it easily. Many user-
friendly statistical software packages are made expressly for that purpose —
Microsoft Excel, Minitab, SAS, and SPSS are just a few. Free online programs
are available, too, such as Stat Crunch, to help you do just what it says —
crunch your numbers and get an answer.
Each software package has its own pros and cons (and its own users and pro-
testers). My software of choice and the one I reference throughout this book
is Minitab, because it’s very easy to use, the results are precise, and the soft-
ware’s loaded with all the data-analysis techniques used in Stats II. Although
a site license for Minitab isn’t cheap, the student version is available for rent
for only a few bucks a semester.

The most important idea when applying statistical techniques to analyze data
is to know what’s going on behind the number crunching so you (not the
computer) are in control of the analysis. That’s why knowledge of Stats II is so
critical.

Many people don’t realize that statistical software can’t tell you when to use
and not to use a certain statistical technique. You have to determine that on
your own. As a result, people think they’re doing their analyses correctly, but
they can end up making all kinds of mistakes. In the following sections, I give
examples of some situations in which innocent data analyses can go wrong
and why it’s important to spot and avoid these mistakes before you start
crunching numbers.

Bottom line: Today’s software packages are too good to be true if you don’t
have a clear and thorough understanding of the Stats II that’s underneath
them.

Remembering the old days

In the old days, in order to determine whether The good news is that statistical software pack-
different methods gave different results, you ages have undergone an incredible evolution in
had to write a computer program using code the last 10 to 15 years, to the point where you
that you had to take a class to learn. You had can now enter your data quickly and easily in
to type in your data in a specific way that the almost any format. Moreover, the choices for
computer program demanded, and you had to data analysis are well organized and listed in
submit your program to the computer and wait pull-down menus. The results come instantly
for the results. This method was time consum- and successfully, and you can cut and paste
ing and a general all-around pain. them into a word-processing document without
blinking an eye.

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