The primary advantage of using a graph or chart in a presentation is that they help the audience to visualize the point of the presentation. Graphs emphasize the main point, make the data more convincing, provide a compact way of presenting information and help audiences stay engaged. Disadvantages of graphs include being time consuming to construct and costly to produce. They also require technology that some may lack.
Graphs have several purposes, including showing and comparing data and illustrating facts. Seven main types of graphs exist: the bar or pareto graph, the pie chart or circle graph, the histogram, stem and leaf plots, dot plots, scatterplots, and time-series graphs. Bar or pareto graphs show a bar for each category or set of data that is qualitative. Pie graphs show data in the form of a pie, and each piece of the pie represents a different data set. Histograms look similar to bar graphs, and they illustrate quantitative and not qualitative data. Stem and leaf plots illustrate quantitative data and emphasize the high point in the data. Dot plots are combination of histograms and stem-and-leaf plots. Scatterplots use correlation and regression to show trends. Time-series graphs display data at different points in time.