Supporting Resources
Levels of Measurement
Examples:
- Topographic
feature codes (from BC Ministry of Environment): NOMINAL
(just names) (an excerpt
if those happen to move...)
- Map legend
for National Wetland Inventory Cowardin classification [the
official text]; Look up each code from the FWS NWI Cowardin
codes. (Nominal, but multi-level concatenation of independent
features...) [Subvert their system, ask for M1RF1b: a coral reef
with beaver habitat, it is not "questionable"...]
- In riparian mapping at Fish and Wildlife, "dominant"
is 30% or more... (ordinal?)
- Matthews Datasets
- Earthquake
damage maps for Western Washington; what kind of attribute
is this? Ordered categories=ordinal...; fill in their survey
about movement - most questions are ORDERED categories...
- Interval, relatively few actually (the current
UW weather observations are all ratio data except the degrees
F, the wind direction also has an arbitrary zero - it is cyclical)
- Ratio: the SI
system (note the distinction between base units and "derived");
NIST Office of Weights and Measures: Virtual
Museum (some neat stuff...)
Comprehensive legislation on measurement; example of Indiana,
Washington,
(less comprehensive actually)
Stories about Measurement Failures
The ones that are easily documented deal with mistakes in units
of measurement. It is harder to amass stories about mistakes about
levels of measure (confusing ordinal with ratio?), partially because
they are institutionalized.
Air Canada 757 ran out of fuel in the 1980s when the plane
was new. Somehow no one noticed that the plane operated in liters
not gallons. (This is the one that landed dead-stick at the closed
military airbase in the midst of the go-cart rally.)
The Mars probe crashed into the planet due to miscommunication
between Lockheed-Martin and JPL over the use of English (pound
of force) versus metric units (newton). [1999 story still
available at CNN]
This list could go on... (Any ones to add?)
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Version of 1 October 2003