Lines on maps Flashcards
Describe radial lines
data radiates outwards from a central point. Data is plotted at points on the line which are joined or segments. Every variable uses the same scale.
When should you use radial lines?
To show the relationship of continuous variables to a central point.
What are the strengths of using radial lines?
Show relationship of many variables to a central point.
Can show direction (compass points)
Can compare different subjects easily - overlap polygons.
Shows data trends-(high/low/outlier).
What are the weaknesses of using radial lines?
Limited data applies.
Difficult to read exact data if overlaps
Difficult to find a suitable scale when data has a wide range of values.
Describe desire lines
straight arrows pointing from the source to the destination of movement.
When should you use desire lines?
To show the direction of movement.
What are the strengths of using desire lines?
Shows direction of movement
Shows spatial distribution
Clear/visual
What are the weaknesses of using desire lines?
Doesn’t show volume of movement
Many lines can overlap and become unclear
Take no account of route.
Describe flow lines
arrows pointing from source to destination, arrow width shows the volume of movement.
When should you use flow lines?
To show the amount of and direction of movement.
What are the strengths of flow lines?
Shows DIRECTION and VOLUME > as width of lines proportional to value
Can give exact data
Clear/visual
What are the weaknesses of flow lines?
Many lines can overlap and become unclear.
Difficult to construct and read scale for proportional flow lines if range of values is large.
Describe isolines
lines on a map joining all points of equal value. Key types: coutours (equal height); isobars (equal pressure) and isovels (equal velocity (speed).
When should you use isolines?
To show data and distribution when change is gradual.
What are the strengths of isolines?
Shows DATA and DISTRIBUTION
Can see areas of equal value
Can see gradual changes
