Brain Eating Amoeba ECA-RS

The second random sampling technique is called presence/absence.  This procedure is used if you simply want to determine if the organism you are looking for is present. You do not create a grid or select squares in the grid to count.  Instead, you randomly pick individual points to sample.  The more samples that are taken in the presence/absence method, or in any general research, the better. The only restraint to taking more samples is the time it takes, and resources needed to do the experiment.

In presence/absence sampling if you know that what you are looking for lives most often in a specific niche in your environment, then you should randomly sample these sections more often. For example, protozoans like amoeba are often found in the water and lose sediment of the littoral zone of a lake.  The littoral zone is the shallow edge of a lake or pond.  Also, any additional information you know about the organism you are sampling should be taken into consideration, such as it is hard to find.