Line charts show trends in continuous data over time. They are commonly used in business and the stock market to show profit fluctuations. Usually, the dependent variable, such as profit, is plotted on the y-axis, while the independent, such as time, is plotted on the x-axis. Line charts' other advantages are that plotting more than one on the same chart makes it easy to compare data at a glance, and seeing trends over time facilitates making predictions.
Scatter plots show trends in discrete data in the way line plots show trends in continuous data. Since the data being compared is discrete, rather than a line connecting every point, a line of best fit is drawn through the scattered points to highlight the general trend in the data. For example, if the y-axis represents money earned and the x-axis the days of the week, and the company earns $50,000 on Tuesday, a mark is made at the intersection of $50,000 and Tuesday. If the company generally earns more each day, the line of best fit slopes upward.
Bar graphs compare trends in discrete data sets by making them into vertical columns. A bar graph showing precipitation in a given year would have months on the x-axis and units of precipitation on the y-axis. The more precipitation in a month, the higher its bar will be, thus making it easy to compare precipitation month by month. Histograms are bar graphs for showing continuous data, such as rainfall per second. There are no spaces between columns on histograms.
Pie charts show the size of parts in relation to the whole by making each piece of data a slice of the greater, circular pie. Pie charts are often used to show how budgets are being spent or time is being used, since they make it easy to see proportions at a glance. Disadvantages of pie charts are that they make it difficult to compare two different sets of data, such as budgets from two different years, and they can only effectively show six or seven chunks, or slices of data.
Box and whisker plots are ways of plotting statistical information along a number line. The mean is a vertical line drawn above its corresponding point on the number line, in the middle of a box drawn around lines at the point of the data's upper and lower quartiles. Horizontal lines called whiskers extend from this box to vertical lines drawn above the data's upper and lower extremes. Drawing several of these makes it easy to compare large data sets, but exact values often become obscured