Symbolisation and Visual Variables Questions and Answers

Answer: A

Bertin set out size, value, texture, colour hue, orientation and shape as the properties that can be varied independently of position. Choosing among them is the central act of symbol design, because each carries a different kind of meaning.

Answer: B

Size is read quantitatively: a circle twice the area is understood to represent more. Shape, hue and orientation are read as differences in kind rather than in amount, so they cannot carry a magnitude without a legend doing all the work.

Answer: C

Hue separates without implying order, so green forest and blue water read as different rather than as more and less. Size, value and grain all suggest a sequence, which would mislead a reader looking at unranked categories.

Answer: D

Correct answer: the lightness or darkness of a tone

Value is one of Bertin’s visual variables and means lightness alone - how much black or white a tone contains, independent of its hue and its saturation. Because the eye reads light and dark as ordered, value is the variable that carries quantity in a choropleth, and it is the one that survives conversion to greyscale.

Answer: A

Hues have no natural order, so a reader cannot tell whether red outranks green without consulting the legend each time. Value or a single-hue sequence of increasing darkness carries order directly and should be used instead.

Answer: B

Both statements are true and the reason accounts for the assertion: because the data being shown are ranked, the symbol must be read as ranked too, which a light-to-dark progression achieves and a collection of separate hues does not.

Answer: C

Correct answer: a rate or ratio calculated for each unit

Shading a whole unit implies that the value applies everywhere within it, which is only defensible for a rate or ratio - density, percentage, per capita figure. Shading a raw total instead makes a large unit look intense merely because it is large, so the map ends up displaying the shape of the reporting units rather than the distribution. Normalising is not optional on a choropleth.

Answer: D

A total depends on the size of the unit as much as on the phenomenon, so a large sparsely settled district can outshade a small crowded one. Standardising to a density or a percentage first is what makes the comparison fair.

Answer: A

Because the symbol sits at a point rather than filling an area, it can carry a raw total without the unit-size problem that affects choropleth maps. The reader compares areas of circles instead of densities of shading.

Answer: B

Correct answer: placing dots of equal value across the area

Each dot stands for a fixed quantity, and the dots are placed where the phenomenon is believed to occur rather than spread evenly over the unit. Density then reads directly as intensity. The technique’s advantage over the choropleth is that it shows variation *within* a unit; its weakness is that the placement is an interpretation, and a reader cannot recover the underlying figures by counting.