Which one of the following methods is best suited for mapping the distribution…
2011
Which one of the following methods is best suited for mapping the distribution of different crops as provided in the standard classification of crops in India ?
Answer: B. Chorochromatic technique — Concept — A thematic map is chosen by the measurement level of the data it has to carry. Data that record a kind or type — nominal, qualitative categories…
- A.
Pie diagram
- B.
Chorochromatic technique
- C.
Isopleth technique
- D.
Dot method
Attempted by 4 students.
Show answer & explanation
Correct answer: B
Concept — A thematic map is chosen by the measurement level of the data it has to carry. Data that record a kind or type — nominal, qualitative categories that differ in what they are and not in how much there is — are shown by giving every category its own colour or shade and spreading that colour over the ground the category occupies. That colour-patch treatment is the chorochromatic technique. Data that record an amount are handled by other devices: a counted quantity by dots, a quantity that varies continuously by lines of equal value, and the share-out of one total at a place by a divided circle.
Application — The standard classification of crops in India sorts cultivated land into classes of kind — food grains, cash crops, plantation crops, horticultural crops, and within them rice, wheat, cotton, sugarcane, tea and so on. These classes are categories, not magnitudes: a tract is a wheat tract or a cotton tract, it is not "more" or "less" of a crop class. The mapping therefore assigns each crop class its own colour or shade and fills in the tract over which that class dominates, so the finished sheet reads as a mosaic of coloured patches whose edges are crop-region boundaries. That is precisely what the chorochromatic technique produces, and it is why the chorochromatic technique is the one best suited to mapping the distribution of the different crops of India.
Cross-check — the three other devices are tested against the same requirement, namely showing which crop class holds which tract:
Method | What the sheet actually shows | Why it does not answer this stem |
|---|---|---|
Dot method | One dot stands for a fixed number of units of a single counted item, so the sheet reports how much of that one thing is present. | With several crop classes on the same sheet it reports quantity, not which class holds which tract; it suits the acreage or output of one crop. |
Isopleth technique | Lines are drawn through places of equal value of a quantity that can be measured anywhere and changes gradually, such as rainfall, temperature or crop density. | Crop classes are discrete kinds with no intermediate values, so there is no continuous surface to contour. |
Pie diagram | One circle is cut into sectors proportional to the parts of a single total, reporting the composition of that total at a point or for one administrative unit. | A scatter of such circles reports shares at chosen places and never delineates the areal extent of a crop region. |
Because the data here are categories of kind spread over area, the colour-patch treatment fits and the quantity-based devices do not: the chorochromatic technique is the appropriate method.