Week 6: Geographic Data and Methods

Question 1

List 3 features of representation.

Answer 1

• Needed to convey information
• Fit into a standard form
• Simplifies the truth

Question 2

How is representation affected through photography?

Answer 2

Black and white photos remove data due to lack of colour

Question 3

What is digital representation?

Answer 3

Binary - uses only two symbols, 0 and 1, to represent information

Question 4

Why are representations rarely perfect?

Answer 4

• Details can be irrelevant
• Too expensive or voluminous to record

Question 5

List 5 different attributes.

Answer 5

• Nominal
• Ordinal
• Cyclic
• Interval
• Ratio

Question 6

Where do cyclic attributes commonly occur?

Answer 6

In GIS

Question 7

List the characteristics of raster representation.

Answer 7

• Pixel size
• The size of the cell or picture element, defining the level of spatial detail
• All variation within pixels is lost
• Assigning reality into pixels
• The value of a cell may be an average over the cell, or a total within the cell, or the most common value of the cell

Question 8

List the characteristics of vector representation.

Answer 8

• Used to represent points, lines and areas
• All are represented using coordinates
• one per point
• Areas as polygons
• Straight lines between points, connecting back to the start
• Point locations recorded as coordinates

Question 9

What does MAUP stand for?

Answer 9

Modifiable Areal Unit problem

Question 10

How do census output areas try and minimise MAUP?

Answer 10

• Seek to standardise the number of people in each area
• Roughly group according to socioeconomic characteristics
• Try not to cross major barriers such as rivers/parks etc.

Question 11

What is ecological fallacy?

Answer 11

The problem of making inferences about individuals from aggregate data, for example causing the assumption that all individuals in a group share the same average characteristics.