Displaying Data
Quantitative vs. Qualitative Data
Symbolizing Features: Qualitative
Symbolizing Features: Quantitative
Qualitative Symbology

Different features get different symbols or
colors, it is not dependent on a quantitative
value. Limit to 10 unique values generally.
Same symbol
Unique symbol (value)
Quantitative Symbology

Uses values, or quantities, contained in
numeric attribute fields
Graduated colors:
The color varies with the
numeric attribute value,
Usually the dark the color
The higher the value.
Up to 5 or 6 shades of one
color maximum.
Quantitative Symbology

Graduate Symbols
The symbol size varies with
the attribute value.
Usually the larger the symbol
the greater the value.
This shows relative values,
not absolute values.
Quantitative Symbology

Proportional symbols
Symbols vary in size
to show exact values.
Normalizing Data

Quantitative symbology can be normalized
based upon the attributes of another field.

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For example population normalized by area
Sales per state normalized by population.
Normalizing data
Displaying multiple attributes

Symbolize features based on more than
one attribute.


Street type and traffic volume.
Parcel land use and value.
Quantitative Symbology

Dot Density
Good for showing
areas of low and
high concentrations
Classifying the data based upon attribute value
Default
Classification places attribute values into
groups



Natural breaks (default) – the gaps in the data
are identified and the intervals are assigned
accordingly. Shows clusters or concentrations
of values.
Equal interval – range of values is equal within
each class (61-70, 71-80, 81-90, etc.) Bands of
temperature.
Quantile – the number of features with in each
class are the same (top 25%)
Classifying the data based upon attribute value


Standard Deviation- the range of values
with each class is based on the standard
deviation of the data. Shows the amount
the attribute value varies from the mean.
(crops which area perform better than
average, which perform worse than
average)
Manual – defined by the user.
Histograms