what is Dot mapping
technique that involves using the quantity of a symbol to represent the geographic distribution of a phenomena
what does is dot mapping goo at representing
relative density if a Phenomena
what are the two types of dot maps
- one to one, Each dot = one occurrence
- Many to one, each dot multiple occurrences
what are the advantages of point density
- ease of interpretation
- recovery of orginal data
- ability to portray more than one distribution
- ease of construction
disadvantages of point density
- inaccuracies in perception
- difficulty in extracting original data
- large data ranges make selecting dot values difficult
- time required to construct.
what is a good size of areal units
smaller AU are better
restrict dot location
what are the two considerations of dot density symbology
dot value, and size
how can you increase perceived accuracy
dot value decrease and dot size decrease
what is a good way to determine ideal dot size
to have at least 2 or 3 dots in the smallest enumeration unit
how do you choose the best dot size
when dots just begin to coalesce in the highest density area
when do dot maps not work well
- for small range datasets
- data with extremely large attribute ranges
what does dot placement depict?
- clustering
- linearity
- exclusion
what are some considerations of dot placement
- regular geometric arrangements
- creating false boundaries
- boundary awarness
how do you create a dot map legend
create units that show number of dots and what the equal. A statement of how much one dot represents
