Page 60 - Statistics for Dummies

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All research starts with a question, such as:
✓ Is it possible to drink too much water?
✓ What’s the cost of living in San Francisco?
✓ Who will win the next presidential election?
✓ Do herbs really help maintain good health?
✓ Will my favorite TV show get renewed for next year?
None of these questions asks anything directly about numbers. Yet each
question requires the use of data and statistical processes to come up with
the answer.
Suppose a researcher wants to determine who will win the next U.S. presiden-
tial election. To answer with confidence, the researcher has to follow several
steps:
1. Determine the population to be studied.
Part I: Vital Statistics about Statistics
In this case, the researcher intends to study registered voters who plan
to vote in the next election.
2. Collect the data.
This step is a challenge, because you can’t go out and ask every person
in the United States whether they plan to vote, and if so, for whom they
plan to vote. Beyond that, suppose someone says, “Yes, I plan to vote.”
Will that person really vote come Election Day? And will that same
person tell you whom he actually plans to vote for? And what if that
person changes his mind later on and votes for a different candidate?
3. Organize, summarize, and analyze the data.
After the researcher has gone out and collected the data she needs,
getting it organized, summarized, and analyzed helps the researcher
answer her question. This step is what most people recognize as the
business of statistics.
4. Take all the data summaries, charts, graphs, and analyses and draw con-
clusions from them to try to answer the researcher’s original question.
Of course, the researcher will not be able to have 100% confidence that
her answer is correct, because not every person in the United States was
asked. But she can get an answer that she is nearly 100% sure is correct.
In fact, with a sample of about 2,500 people who are selected in a fair
and unbiased way (that is, every possible sample of size 2,500 had an
equal chance of being selected), the researcher can get accurate results
within plus or minus 2.5% (if all the steps in the research process are
done correctly).

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