Page 87 - Statistics for Dummies

These data confirm the widely accepted notion that women tend to live
longer than men. However, the gap between men and women is narrowing
over time. According to the U.S. Census Bureau, back in 2001 the percentage
of women who were 80 years old and over was 4.36, compared to 2.31 for the
men. The females in this age group outnumbered the males by a whopping
89% back in 2001 (note that [4.36 – 2.31] ÷ 2.31 = 0.89).
After you have the crosstabs that show the breakdown of two categorical vari-
ables, you can conduct hypothesis tests to determine whether a significant
relationship or link between the two variables exists, taking into account the
fact that data vary from sample to sample. Chapter 14 gives you all the details
on hypothesis tests.
Measuring the Center with
Mean and Median Chapter 5: Means, Medians, and More 71
With numerical data, measurable characteristics such as height, weight, IQ,
age, or income are represented by numbers that make sense within the con-
text of the problem (for example in units of feet, dollars, or people). Because
the data have numerical meaning, you can summarize them in more ways
than is possible with categorical data. The most common way to summarize
a numerical data set is to describe where the center is. One way of thinking
about what the center of a data set means is to ask, “What’s a typical value?”
Or, “Where is the middle of the data?” The center of a data set can actually
be measured in different ways, and the method chosen can greatly influence
the conclusions people make about the data. This section hits on measures
of center.
Averaging out to the mean
NBA players make a lot of money, right? You often hear about players like
Kobe Bryant or LeBron James who make tens of millions of dollars a year.
But is that what the typical NBA player makes? Not really (although I don’t
exactly feel sorry for the others, given that they still make more money than
most of us will ever make). Tens of millions of dollars is the kind of money
you can command when you are a superstar among superstars, which is
what these elite players are.

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