Random Compass Coordinates Diagrams





Figure 2.8a. This diagram shows how a randomly selected compass bearing (in this case, 48 degrees) and a randomly chosen distance (in this case, 12 m) can be used to locate a randomly selected point within your field site. (Obviously, the compass face is not drawn to scale!)






Figure 2.8b. Selection of a second randomly chosen point (y) based on a new compass bearing and distance.






Figure 2.8c. This diagram shows the results of choosing a number of randomly selected points based on compass bearing and distance. There are several important issues to keep in mind when using this method: it's wise to begin this method near the middle of your field site to be sure that your first few points will be located within your site; once near the edge of your site, throw out any compass bearing/distance combinations that take you out of your site; you should constrain the minimum and maximum distances that are generated based on the details of your field site and your sampling design (see the appropriate random number tables here for more details); this method is prone to repeat sampling, so it's important to keep track of locations already sampled - for example, if measuring trees, tree bark can be marked with chalk so that the tree is not sampled again.





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