Isopleths and Choropleth maps

Question 1

spatial data definition

Answer 1

data from areal patterns (locations)

Question 2

choropleth map definiton

Answer 2

a quantitative areal map that displays spatial variations in values between areas by colour or shading

Question 3

isolines/isopleths

Answer 3

lines on a map that join places of equal value. they are derived from point measurements, but aren’t appropriate for representing geographically discrete phenomena like land use or population

Question 4

Isopleths advantages

Answer 4

• visual
• easy to draw
• gives indication of gradient

Question 5

Isopleths disadvantages

Answer 5

• selection of interval value between isopleths is crutial (too big=inaccurate, too small=map becomes obscured by lines)
• involves assumption which may be wrong e.g. if one value is 10, the other is 20, 15 is in the middle

Question 6

Choropleths advantages

Answer 6

• different shading makes it easy to understand

- shows patterns easily

Question 7

Choropleths disadvantages

Answer 7

• treats the area a a whole so hides variations
• shading may be unclear
• assumes everywhere is the same (uniform values) which isn’t usually true=misleading

Question 8

Choropleths uses

Answer 8

use standardised data e.g. ratios, percentages and averages

-areal units are shaded based on values

Question 9

isopleth uses

Answer 9

Physical: e.g. precipitation, temperature, contor lines=gradient
Human:e.g. journey time,transport, land values, pedestrian density