Thematic Mapping Techniques Questions and Answers

Answer: A

A surface of rainfall or temperature is built by estimating values at places where no reading was taken. The method chosen, whether inverse distance or kriging, changes the surface, so it forms part of the map's documentation.

Answer: B

Each method makes different assumptions about how influence falls off with distance, so the surfaces differ, sometimes markedly, between the observation points. They agree only at the observations themselves, where the data pin them down.

Answer: C

Correct answer: transparency according to a second variable

A value-by-alpha map shades the units by the rate of interest in the ordinary way and then varies the opacity by a second variable, usually population, so that thinly populated units fade towards the background. It addresses the choropleth’s central distortion - that a large empty district shouts as loudly as a small crowded one - without the shape distortion a cartogram brings.

Answer: D

The data are genuinely discrete, so a display that spreads them across an area would imply a continuity that does not exist. Density surfaces may be derived from the points afterwards, but the points remain the observation.

Answer: A

The first two are sound. The third is wrong, because a legend explains the symbols while the title establishes the subject, the extent and the date, none of which the legend supplies. A reader meeting the sheet out of context has only the title to go on.

Answer: B

Choosing the variable, the denominator, the classification and the colours all shape what the reader sees, and none of them has a default. Acknowledging that the map argues something is more honest than claiming it merely reports.

Answer: C

Geology, land use and vegetation maps fill each area with a colour standing for a kind rather than an amount. The technique carries no order at all, which is exactly why hue rather than value is the right variable to encode it.

Answer: D

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason is the principle. Rock types are a nominal category: sandstone is not more or less of anything than granite, so a sequence of tones running light to dark would imply an order that does not exist. Unrelated hues signal difference in kind. A graded sequence is reserved for data that genuinely are ordered, and that is the basic rule linking data type to visual variable.

Answer: A

Multiplying 68 dots by the value of 250 gives 17,000. Reading a dot map backwards this way is only approximate, since dots at the edges of dense clusters are difficult to count reliably and some may overlap entirely at that density.

Answer: B

Coincidence between patterns drawn on different sets of boundaries can be an artefact of the units rather than a relationship in the data. This is the modifiable areal unit problem appearing in a comparison rather than in a single map.