A bar chart is used when you want to show a distribution of data points or perform a comparison of metric values across different subgroups of your data. From a bar chart, we can see which groups are highest or most common, and how other groups compare against the others.
Bar charts are used for minor works because
(1) The bar chart does not show clearly the inter-relationships of all activities. This requires the dependence of one activity upon another to be remembered by the planner. This is extremely difficult when a project involves a large number of activities.
(2) When a delay occurs in a large project, many activities tend to be crashed unnecessarily as it is almost impossible to remember which activities in the bar chart are interdependent.
(3) The horizontal lines in the bar chart can be readily juggled to fit them within the specified or compressed period of completion.
(4) Bar charts do not indicate critical areas of work that primarily constrain project completion and require greater attention from the management. In the absence of such an indication, the management is compelled to concentrate on all activities at all times with equal attention.