Dot map are statistical map which use dots of fixed size to represent a fixed number of units in particular area. They employ a base map of a concerned area and a dot are drawn exactly on appropriate location on the map. they are useful in representing statistical data like population, plants in the forest and so on.
The following are procedures used to construct dot maps:
- Obtain the base map of the area you want to represent and divide it into required sub regions.
- Obtain and tabulate the data you want to represent corresponding with sub regions in the base map.
- Make a scale and estimate how many items will be represented by one dot.
- Compute the number of dots to represent total items in each regions by using the scale
- Insert dots in particular sub regions depending on the total items to be represented as computed earlier
- Label and give appropriate title to your map.
Dot map has the following shortcomings.
- They do not show the absolute values on the map, rather they show dots.
- It is difficult to represent fraction on by using dots, though fraction may happen in tabulated data.
- It may lead to confusion if too many dots has to be drawn on relatively small area.
- It is relatively difficult to interpret when the small scale is used, for example, if the scale show that one dot represent 200000 items, the regional with 200000 units may seem to have few items and this can be misleading.
- Small area with clustered dots, may give the impression that it has more of the items than the large region with scattered dots of the same number or more.
Advantages and disadvantages of dot maps.