The bar charts and the pie charts are both a form of visual communication used in data presentation. They differ in the type and magnitude of the data that they can present. Many people prefer using charts because they find it easy to obtain the information they need. There are different types of charts. The type of chart that is most applicable will depend on the type of information to be presented. Bar charts and pie charts are the most popular types of charts. Bar charts use vertical or horizontal bars on an axis to represent values. They are mostly used to compare values for different categories. The bars can be either horizontal or vertical, and they are arranged in a logical order. It is easy to compare data when the bars are arranged from the largest to the smallest or vice versa, depending on the orientation used. The bars are the same width but their heights vary to reflect the changes in the size or value of the items. The spaces are separated by gaps, and are usually bigger than the gaps (UNECE, 2009). Data can be from different variables collected in the same period, or it can be a comparison between different periods. They are simple to use and easy to understand.
Pie charts are a form of a graph that represents data on a circle. They are used to show the percentage of a single variable. One cannot use one pie chart to compare different variables. Pie charts compare different components to a whole. Pie charts offer more limited options than bar graphs because one pie represents all the data. Pie charts are only used when one is dealing with few categories. The segments represent a percentage of the item, thus, the higher the percentage, the bigger the segment. People find it hard to determine the percentage of data indicated in a pie chart, especially if the percentages are close. However, many people label the segments, and they indicate their percentages so that they can understand the data easily. Moreover, pie charts can be tedious to construct (Smithson, 2000).
Smithson, M. (2000). Statistics with confidence. Thousand Oaks, CA: SAGE
UNECE (2009). Making data meaningful part 2: A guide to presenting statistics. United Nations Economic Commission for Europe. Retrieved from www.unece.org/stats/documents/writing/MDM_Part2_English.pdf