Symbolisation and Visual Variables Questions and Answers

Answer: A

Doubling the radius quadruples the area the eye actually compares, so the larger circles look far greater than they are. Scaling by area is the standard correction, and Flannery's adjustment goes further to allow for systematic underestimation.

Answer: B

Experiments showed that readers systematically judge large circles as smaller than they are, so a strictly area-proportional scale still understates the top of the range. The adjustment enlarges bigger symbols slightly to compensate.

Answer: C

The first and third describe standard practice, since area scaling matches perception and a three-value legend lets the reader interpolate. The second is wrong, because deleting symbols removes data, while transparency or outlining preserves it.

Answer: D

Correct answer: water features such as rivers and lakes

Blue is reserved for hydrography - rivers, lakes, coastlines, marshes and the names that go with them. The topographic colour conventions are consistent enough across national series to be worth learning as a set: blue for water, brown for relief, green for vegetation, black for constructed detail and names, and red for major roads and selected features.

Answer: A

Correct answer: contours and relief

Brown carries the relief: contours, their values, spot heights on some series, and features such as cuttings, embankments and sand. Keeping relief in its own colour lets the contours run beneath the black detail without confusing it, which matters because contours cross everything else on the sheet.

Answer: B

Even conventional symbols vary between agencies and countries, and a reader cannot know which set is in use. A legend also records the dot value, the class limits and the symbol scale, none of which convention can supply.

Answer: C

Beyond roughly seven steps most readers cannot match a shade on the map to the right box in the legend. Fewer classes read more clearly, at the cost of grouping together values that genuinely differ. Between four and seven classes is the usual compromise.

Answer: D

Both hold, and the reason gives the mechanism: once a range is assigned one shade, the differences inside that range become invisible. The compensation is a map the reader can actually decode, which an unclassed version often is not.

Answer: A

Equal interval cuts the range into steps of the same size, which is easy to read but can leave classes empty when the distribution is skewed. Quantile, natural breaks and standard deviation schemes each answer that problem differently.

Answer: B

Correct answer: an equal number of units in each class

Quantile classification puts the same count of observations in each class, so with five classes and a hundred units each class holds twenty. The result fills the legend evenly and always produces a visually balanced map, but it can place very similar values in different classes and very different ones in the same class - which is why equal interval or natural breaks may represent the data better even when the map looks worse.