Interpreting Figures and Tables

Most students have little or no experience interpreting figures and tables. If you use a logical stepwise way to make sense of data presented in figure or table form, your students might slow down enough to make a careful interpretation.

For examples see Figure 1, Figure 2, and Table 1 below

A- Reading the data:

1- First determine how the figure/table is set up. This is the part that everyone would agree about and is not a matter of interpretation.

a- What are units on the axes (for a figure) or heading of the columns (for a table)? Make sure you understand what these units mean. For example, in Figure 1, the units are millimeters. In Figure 2 the units are degrees Celsius. In Table 1 the units are millimeters and lps.

b- Pay attention to the symbols on a figure, the differences between dotted and solid lines, and so on. For example, in figure 1 and 2 different colors and shapes designate averages over different time intervals.

2- Now look at the pattern in the data.

a- For a figure with lines, what is their pattern? For instance, do they increase linearly and then level off? In a table do the numbers increase across the column? For example, in Figure 2 the average temperatures oscillate within a year. In Table 1 the total precipitation decreases and then increases over the span of the year.

3- At this point you should have a pretty good idea of the question addressed by the data set and how the experiment was carried out. For example, in Table 1, the authors were looking at total precipitation for each month in 1996. The question may have been, what is the overall pattern of precipitation over a year at Lookout Creek?

B- Interpreting the data:

a- What conclusions can you draw from the pattern that you have described? For example, based on Table 1 and Figure 1, you can conclude that there is a dry season and a rainy season almost every year at Lookout Creek. Figure 2 suggests that the dry season corresponds to warmer season, where temperatures are on average at their highest.

b- What do these results tell you about the phenomenon being studied?

c- How do they fit into the larger picture of ecological thinking?

Interpretations may well differ from person to person; this is to be expected and makes discussions about data sets all the more interesting!

Figure 1:Monthly mean precipitation data for H.J. Andrews Experimental Forest Upper Lookout Creek Meteorological Stations

Figure 2: Monthly mean air temperature for H.J. Andrews Experimental Forest Upper Lookout Creek Meteorological Stations


Table 1: Monthly percipitation and stream discharge data, Lookout Creek, 1996