Description: Bar charts drawn for several categories of information (in this case three) that are drawn directly onto the area in which the measurements were taken. The one below is for percentage of people living in Owner Occupied, Private rented or council rented accommodation in each area. The bar charts need a scale and a key.
Method: Convert all values to percentages, decide on an appropriate scale for the bar charts, the scale needs to show the variation within the categories, but not be so large as to obscure the map. Locate a suitable point within each region to draw the bar chart, and try to ensure that the entire bar chart can be located within the region.
Benefits: Allows for multiple pieces of data to be clearly represented on the map, the result is clear and easy to read, highly visual and not too complicated. The graph does not require any special equipment, and the only maths involved is to convert to percentages, which is essential for comparison.
Disadvantages: Can only be used for a few pieces of data, too many and it becomes hard to read. Deciding on a scale can be difficult if there is a considerable amount of variation across the regions, as some bars will be very small. It can be quite time consuming, as each region will need a different graph.
Best used for: Data with several variables, but can be used for any type of data that is converted to a percentage. In the case of this AIB, the percentage of people in each type of housing, or the percentage in each type of employment would be suitable.