how to read graphs
1 Line graphs give you 1 piece of explicit information that bar graphs don't. 2  The steepness of the line connecting each data point on the graph (that is, each dot) indicates the rate of change. 3  A steeply descending line, for example, would show that salmon returns dropped abruptly from 1 month to the next. For example, you might want to know how many salmon returned to the stream in question in August of last year. 2  So you'd read across the graph's horizontal axis until you find August.. 3  Time elements, such as days, weeks, months or years, are almost always listed along the horizontal (x) axis.