Page 35 - Statistics for Dummies

Chapter 1: Statistics in a Nutshell
population. For example, a politician may claim that 80% of the people in her
state agree with her — is that really true? Or, a company may claim that they
deliver pizzas in 30 minutes or less; is that really true? Medical researchers
use hypothesis tests all the time to test whether or not a certain drug is effec-
tive, to compare a new drug to an existing drug in terms of its side effects,
or to see which weight-loss program is most effective with a certain group of
people.
The elements about a population that are most often tested are
✓ The population mean (Is the average delivery time of 30 minutes really
true?)
✓ The population proportion (Is it true that 80% of the voters support this
candidate, or is it less than that?)
✓ The difference in two population means or proportions (Is it true that
the average weight loss on this new program is 10 pounds more than
the most popular program? Or, is it true that this drug decreases blood 19
pressure by 10% more than the current drug?)
Hypothesis tests are used in a host of areas that affect your everyday life,
such as medical studies, advertisements, polling data, and virtually anywhere
that comparisons are made based on averages or proportions. And in the
workplace, hypothesis tests are used heavily in areas like marketing, where
you want to determine whether a certain type of ad is effective or whether a
certain group of individuals buys more or less of your product now compared
to last year.
Often you only hear the conclusions of hypothesis tests (for example, this
drug is significantly more effective and has fewer side effects than the drug
you are using now); but you don’t see the methods used to come to these
conclusions. Chapter 14 goes through all the details and underpinnings of
hypothesis tests so you can conduct and critique them with confidence.
Chapter 15 cuts right to the chase of providing step-by-step instructions for
setting up and carrying out hypothesis tests for a host of specific situations
(one population mean, one population proportion, the difference of two pop-
ulation means, and so on).
After reading Chapters 14 and 15, you’ll be much more empowered when you
need to know things like which group you should be marketing a product
to; which brand of tires will last the longest; whether a certain weight-loss
program is effective; and bigger questions like which surgical procedure you
should opt for.

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