Seeking Trends with Line Graphs

The advantage of a bar graph is that the categories aren't organized in any special way you can write them alphabetically or in any order you want, resulting in different patterns of high and low bars in the bar graph. However, if the categories are related to each other by time, then they should appear in specific chronological order, and the bars in the bar graph can appear in only that specific way. The idea is to be able to predict the future by looking at the trend in the heights of the bars. To make it easier to visualize these trends, a line graph is used; instead of bars, points of data are constructed at the top center of the bars and those points are connected. The bars themselves are erased so as not to block the view of the time-related trend. An example of a time-related line graph could be quarterly financial reports of a company's profits over two years: