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Stat 240.Handout 3.
Measures of center (or location) (Ch2.4),
Measure of variations (Ch 2.5)
Graphs provide a global/qualitative description of a
sample, but they are imprecise for use in statistical
inferences.
We use numerical measures which can be calculated
for either a sample (these measures are called statistics)
or a population (parameters).
- Measures of location.
-Measures of variability.
•
Household Income Rises, Poverty Rate Declines,
Number of Uninsured Up
•
Real median household income in the United States climbed
between 2005 and 2006, reaching $48,200, according to a report
released today by the U.S. Census Bureau. This is the second
consecutive year that income has risen.
•
Meanwhile, the nation’s official poverty rate declined for the first
time this decade, from 12.6 percent in 2005 to 12.3 percent in 2006.
There were 36.5 million people in poverty in 2006, not statistically
different from 2005. The number of people without health insurance
coverage rose from 44.8 million (15.3 percent) in 2005 to 47 million
(15.8 percent) in 2006.
•
These findings are contained in the
Income, Poverty, and Health
Insurance Coverage in the United States: 2006 report
•
http://www.census.gov/cps
•Real median household income of white households rose
1.1 percent between 2005 and 2006 (from $50,100 to
$50,700), the first real increase in annual household
income for this group since 1999. Asian households had
the highest median income at $64,200, followed by non-
Hispanic white ($52,400), Hispanic ($37,800) and black
($32,000) households. Income levels remained statistically
unchanged between 2005 and 2006 for each of these
groups.
•The number of uninsured children increased from 8 million
(10.9 percent) in 2005 to 8.7 million (11.7 percent) in 2006.
Measures of center (or location) (Ch2.4),
• The
mode
: is the sample value that occurs most
frequently.
• The
median
: is the value that falls in the middle position
when the sample values are ordered from the smallest to
the largest.
• The
mean
: is the average value, the balance point.
– The mode can be computed for both qualitative and
quantitative variables.
– The median and the mean we compute for
quantitative variables.