stats & gis

Stats & GIS

Spring 2009

<893 893-1758 1758-2622 2622-3487 3487-4352 4352-5217 5217-6082 6082-6946 6946-7811 7811-86760

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POP2000

<9.5% 9.5%-18.8% 18.8%-28.1% 28.1%-37.4% 37.4%-46.7% 46.7%-56.0% 56.0%-65.3% 65.3%-74.6% 74.6%-83.9% 83.9%-93.2%0

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PCT_OOHU

<7.8% 7.8%-15.6% 15.6%-23.4% 23.4%-31.2% 31.2%-39.0% 39.0%-46.8% 46.8%-54.6% 54.6%-62.4% 62.4%-70.2% 70.2%-78.0%0

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PCT_VACANT

<9.5% 9.5%-18.8% 18.8%-28.1% 28.1%-37.4% 37.4%-46.7% 46.7%-56.0% 56.0%-65.3% 65.3%-74.6% 74.6%-83.9% 83.9%-93.2%0

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PCT_OOHU

OAK-examples.mxd

<9.5% 9.5%-18.8% 18.8%-28.1% 28.1%-37.4% 37.4%-46.7% 46.7%-56.0% 56.0%-65.3% 65.3%-74.6% 74.6%-83.9% 83.9%-93.2%0

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PCT_OOHU

LOOK!

1 std dev

Mean=0.43

Why does ArcGIS switch to a two color scale when I use standard deviation?

WHAT ABOUT BIVARIATE QUESTIONS?

Median % vacant is about 3.5% (in 2000)

Owner Occupancy and Vacancy

• Median owner occupancy was ~36%• Median vacant unit rate was ~3.5%• Can I map above and below on both variables?

0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% 100.00%0%

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% Owner Occupied Hus

% V

acan

t Hus

0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% 100.00%0%

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% Owner Occupied Hus

% V

acan

t Hus

It turns out that…

• “TRUE” = -1• “False” = 0

And so I can create a new field and code it …

• If %VAHU<median add zero• If % VAHU>median add one• If %OOHU<median add zero• If %OOHU>median add two

Low VAHU Low OOHU 0+0=0

High VAHU Low OOHU 1+0=1

Low VAHU High OOHU 0+2=2

High VAHU High OOHU 1+2=3