Make a bar graph of the data in part 1. (For additional information about graphs, see the Scientific Skills Review in Appendix F and in the Study Area in Mastering Biology.)

In part 1 of the study, 12 red-bellied black snakes were collected from established cane toad populations and 12 from previously undeveloped cane toad populations.

Snakes were counted in each region that consumed either freshly killed native frogs (a common prey item for snakes) or freshly slain cane toads with the venom gland removed.

A bar chart or bar graph is a chart or graph that uses rectangular bars with heights or lengths proportionate to the values they represent to convey categorical data. The bars can be plotted either horizontally or vertically.

When displaying massive changes over time, bar graphs work well.

A cause is an independent variable.Other variables have no impact on the value of such a study. The effect is a dependent variable. The changes in the independent variable influence its value.

In the above experiment, time is an independent variable whereas, the populations of predators and prey species are dependent variables.