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, scatter plots, 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, <span>Histograms look similar to bar graphs,</span>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. Scatter plots use correlation and regression to show trends. Time-series graphs display data at different points in time.
This type or graph is used to show comparisons between values, with a bar representing each separate value. Categories or groups are commonly plotted on the horizontal axis (axis X) and a quantitative or numerical scale is plotted on the vertical axis (axis Y). Bar graphs are used to plot both continuous and discontinuous, or discrete, data.
advantages: show each data category in a frequency distribution, display relative numbers/proportions of multiple categories, summarize a large amount of data in a visual, easily intepretable form, make trends easier to highlight than tables do, estimates can be made quickly and accurately, permit visual guidance on accuracy and reasonableness of calculations, accessible to a wide audience
disadvantages: often require additional explanation, fail to expose key assumptions, causes, impacts and patterns, can be easily manipulated to give false impressions
