Page 27 - Statistics for Dummies

Chapter 1: Statistics in a Nutshell
Designing Appropriate Studies
Everyone’s asking questions, from drug companies to biologists; from mar-
keting analysts to the U.S. government. And ultimately, everyone will use sta-
tistics to help them answer their questions. In particular, many medical and
psychological studies are done because someone wants to know the answer
to a question. For example,
✓ Will this vaccine be effective in preventing the flu?
✓ What do Americans think about the state of the economy?
✓ Does an increase in the use of social networking Web sites cause depres-
sion in teenagers?
The first step after a research question has been formed is to design an
effective study to collect data that will help answer that question. This step
amounts to figuring out what process you’ll use to get the data you need. In 11
this section, I give an overview of the two major types of studies — surveys
and experiments — and explore why it’s so important to evaluate how a
study was designed before you believe the results.
Surveys
An observational study is one in which data is collected on individuals in a
way that doesn’t affect them. The most common observational study is the
survey. Surveys are questionnaires that are presented to individuals who
have been selected from a population of interest. Surveys take many differ-
ent forms: paper surveys sent through the mail, questionnaires on Web sites,
call-in polls conducted by TV networks, phone surveys, and so on.
If conducted properly, surveys can be very useful tools for getting informa-
tion. However, if not conducted properly, surveys can result in bogus informa-
tion. Some problems include improper wording of questions, which can be
misleading, lack of response by people who were selected to participate, or
failure to include an entire group of the population. These potential problems
mean a survey has to be well thought out before it’s given.
Many researchers spend a great deal of time and money to do good surveys,
and you’ll know (by the criteria I discuss in Chapter 16) that you can trust
them. However, as you are besieged with so many different types of surveys
found in the media, in the workplace, and in many of your classes, you need

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