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29 Cards in this Set
- Front
- Back
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A comment
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Soil Temperature in degrees. Recorded to the nearest 1/10 of a degree.
Obviously I-R. Obviously quantitative |
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Continued...
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Take that soil variable and reclassify it into classes Cold, Cool, Warm, Hot
The new variable is Ordinal Qualitative |
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What about...
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Take the original soil variable, reclassify it into classes like….
< 68 degrees 68 to 75 degrees > 75 degrees What is its level of measurement? |
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What about...
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Take the original soil variable, reclassify it into classes like….
< 68 degrees 68 to 75 degrees > 75 degrees What is the new variable’s level of measurement? ORDINAL. It is clearly able to be ranked |
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What about...
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Take the original soil variable, reclassify it into classes like….
< 68 degrees 68 to 75 degrees > 75 degrees Qualitative or quantitative? Even though the original data was quantitative, once we make it ordinal, we treat the new form of the data as qualitative, recognizing the imperfection in the designation. |
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Two map flavors
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Topographic maps-shape of the land, cultural features
Thematic maps-show statistics Blue: water Green: vegetation White: snow |
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Topographic maps
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Maps that have topography depiction as the primary theme. However, most also show cultural features too. They are a general map.
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Thematic maps
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Maps designed to show some kind of selected information (frequently statistical) rather than the face of the earth with its physical and cultural features.
-soil moisture regimes |
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Themes abound
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Maximum temperature
Socioeconomic status Land cover Land use Property parcel boundaries Rainfall amounts State of origin (students at BYU) |
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Why map thematic data?
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To arouse greater interest in the subject matter presented
To clarify, simplify, explore, or explain the aspects of a certain spatial phenomena To prove a point in an “argument” To display data that can be mined by other people. |
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Data types
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Interval-Ratio
Nominal Ordinal |
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Interval-ratio
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Data can take on virtually an infinite number of values, dependent on the resolution of the measuring device.
Number of cats born in each state. Dollars spent today on fast food in each city of US Soil temperature at noon, measured in degrees at 100 sample sites on a farm. Elevation above sea level. *most geographic things are interval ratio |
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Ordinal
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*Ordering
Data can only take on a value from a discrete set of names. The names can be naturally ranked (have ordination) from low to high. S.E.S. for each census tract in the state Poor Middle-class Wealthy Soil suitability for growing corn Poor Average Good Class standing in college |
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Nominal
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*Categories
Data can only take on a value from a discrete set of names. There is no natural order of the possible values. Hair color Red, brown, black, blond, Other Brand of computer most people in state use. IBM, Dell, Compaq, Other Soil type measured in zones Marital status Married, unmarried, happy |
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Level of measurement
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Gender (male, female): Nominal
Named class standing (fresh, soph.. ): Ordinal Wind speed in miles per hour: Interval-ratio Balloon flight elevation in meters above sea level: Interval-ratio Dominant species of tree: Nominal Average age of people in years: ? Air temperature in degrees: Interval-ratio |
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The correspond is imperfect
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When we map interval ratio data, we frequently create an ordinal map with class subdivisions. We just don’t have a color for every possible value the data assumed.
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Why care?
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Because as a geographer, the method you use to map data is constrained by the data type.
Because maps generalize data. You need to understand the limits of the map and its data. |
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Caveat
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There is no perfect classification system for thematic maps.
Maps use multiple methods Mixed methods Some just don’t fit anywhere Some fit in multiple slots |
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Thematic maps
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-Proportional symbol map
-Repeated symbols |
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Chloropleth
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-tells us a story;values are mapped by color or shades of grey
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Area Shading
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x
ex) climate classifications |
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Isolines
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represent Quantitative data
ex: rainfall in India; interval-ratio |
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Cartogram
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funky maps
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Dot maps
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each dot represents a certain # of things
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Line map
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x
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Locational map
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x
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Three major types of maps?
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Topographic
Thematic -Cadastral |
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Cadastral map
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-special type of thematic map, but sometimes gets its own category; shows property boundaries
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Expectations
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Be able to recognize different map types.
Recognize the relationship between level of measurement and thematic map type. If I give you a specific problem and three different map choices, select the proper map choice. |
