(GEO455) Unit 8: Point Symbology, Unit 9: Flow Maps

What do we call the existence of one feature or value in symbology?

What 3 variables can differ for Points?

Single representation

Shape, size, and color

Size is a variable normally used for ____ and ____ levels of measurement.

What is point symbology dependent on?

Interval and Ratio

Scale

What do dot density maps communicate?

What must be balanced in a dot density map?

Spatial variability (of density) of discrete geographic data

Dot value and dot size

What kind of map is a proportional symbol map?

How is point data represented in a proportional symbol map?

Quantitative thematic map 

By symbols whose size varies with the data values

What kind of data can we use in a Proportional Symbol Map?

What kind of data can NOT be used?

Raw data or normalized data

Interval level data, density, data with small data ranges

What are the 3 types of scaling for point sizes of proportional symbols? Give an example of each.

(1) Ordinal (Ex: Mega cities, large cities, small cities)

(2) Range-Graded (Ex: 50,000 to 100,000, 100,000 to 250,000, 250,000 to 500,000, etc.)

(3) Absolute Scaling (Ex: 50,000, 100,000, 250,000, etc.)

What is a bivariate dot map?

Points can be _____ or ____ to emphasize multiple variables 

Uses two different symbols to visualize two different data sets.

Color coded; shaded 

What is the main goal of Flow Maps?

What do we call the lines on a flow map? 

Show the movement of objects from one location to another.

Streamlines 

What kind of lines do qualitative flow maps use?

What kind of lines do quantitative flow maps use?

Unscaled lines

Scaled lines

Unscaled lines usually have ____ which indicate ____

Scaled lines have ____ of flow, indicated by ____ or _____.

Arrows; direction (or movement)

Magnitude; width or hue 

What 3 forms of data is used for flow maps?

Proper scaling requires a ____.

What data type cannot be mapped?

Raw data totals, ratios, and proportions.

Real zero

Density

What are 3 of the common units depicted on flow maps?

• Weight

• Volume,

• Value ($)

• Amounts

• Frequencies

What do we call flow maps that use arrows?

What do we call flow maps that don’t use arrows?

What does this imply?

Directed flow maps

Undirected flow maps

Implies movement in both directions

True or False: Flow maps may not follow the actual routes of movement?

True

What are the 3 types of Flow Maps?

What are the two subtypes of origin-destination flow maps?

Origin-Destination, Network, Distributive

Radial vs. Interconnecting

What kind of relationships do origin-destination flow maps depict?

Places are mapped in ____ form

“one-to-many” or “many-to one” relationships

Nodal

Radial maps have _______, while interconnected maps have ________.

A single origin/destination node

Interconnected nodes

What do network flow maps reveal? ________,

Focuses more on the _____ than on the ______.

What are two examples?

interconnectivity of places

Routes ; Nodes

(1) Transportation / transit (2) Communication linkages

What do distributive flow maps present?

What are 3 examples?

the distribution of something

(1) commodities (2) trade flows (3) disease (4) migration (5) diffusion of ideas

In flow maps, what should be the clearest feature?

Flow lines should have _______ and should not _____ with other visual symbols.

Width of lines must be ______ to the quantities represented.

Flow lines (and nodes)

strong edges ; conflict 

proportional

What is range grading?

Classifying the attribute data according to one of the classification schemes used in choropleth maps

How can we differentiate between distributive vs. network flow mapping?

Find out what is being mapped

For each of the three flow maps, name what the main focus of each is:

(1) Origin-Destination

(2) Network 

(3) Distribution 

(1) The nodes

(2) The routes 

(3) Flow of units