Cartographic Data Presentation

Question 1

What is a Choropleth map

Answer 1

A Choropleth map is a thematic map where areas are shaded to show a value eg population density

Question 2

Advantages of a Choropleth map

Answer 2

Easy to construct as you don’t need to know exactly where the data is from, just the country/area.
Good at showing variations in social and economic data with a visually striking impact that is easy to interpret,
Shows distribution of data across an area.

Question 3

Disadvantages of a Choropleth map

Answer 3

It oversimplifies data as it does not show variations within an area.
A poor colour choice can create a striking contrast that may not exist

Question 4

What is a dot map

Answer 4

Show distribution and density of a variable eg population

Question 5

Advantages of a dot map

Answer 5

Effective and simple way to show distribution.
Quantitative map - shows variations in observed numerical data.
Each dot represents a value which means that as long as each dot can be seen variations in a small area are shown unlike a Choropleth map.

Question 6

Disadvantages of a dot map

Answer 6

Where the dot represents a scaled value, low density places are under-represented.
In high density places, obtaining exact and accurate data is difficult as dots merge and overlap.
Scale is crucial as if dots overlap or merge then the map cannot be read accurately.

Question 7

What is an isoline map

Answer 7

An isoline map is a map where areas of the same value are connected.

Question 8

Advantages of an isoline map

Answer 8

Shows a gradual change over a large area unlike a Choropleth map which shows a sharp distinction between boundaries.
It uses fixed intervals so changes can easily be identified.
Colour can be added to enhance patterns without losing accuracy and it make it easier to interpret.

Question 9

Disadvantages of an isoline map

Answer 9

There can be variations in the location of each isoline.
The shading implies equal values between the isolines.
In interpolation (guessing the value between two lines) there is an assumption that change between  the two points is steady when it may not be.

Question 10

What is a proportional symbol

Answer 10

Symbols are drawn on the map proportional to the size of the observed data.

Question 11

Advantages of proportional symbols

Answer 11

Symbols are geo-located.

Easy and quick to interpret, with a visual representation.

Question 12

Disadvantages of proportional symbols

Answer 12

If the scale is too big then all the bars/symbols won’t fit, but too small and it will be had to read.
If the bars are too long they will overlap but too short and you won’t be able to see the difference.

Question 13

What is a flow-line map

Answer 13

Thematic map used to show the movement of object eg trade.

Question 14

Advantages of a flow-line map

Answer 14

Absolute values or percentages can be plotted.
The thickness of the line is proportional to the value.
If lots of lines are going to the same destination then their edges can be merged to reduce map clutter.

Question 15

Disadvantages of flow-line maps

Answer 15

Lines can be basic and layered making it hard to accurately read the map.
As the flow-lines don’t have a scale immediately beside them it is hard to determine the scale, which makes it hard to interpret.