ABSTRACT
There is a wide variety of biodiversity monitoring systems. In this chapter we outline a number of important steps that should be considered when developing a new system or redesigning an old system, from the questions and objectives at the start, through formulating important aspects such as the target population to be monitored, relevant time span for monitoring, and which sources of bias and error different types of monitoring systems might suffer from. Most of the time it is more efficient to focus monitoring efforts on detailed survey of a sample, rather than trying to survey a phenomenon in its entirety. How a sample is selected is important and design-based sampling can be used to avoid selection bias, which otherwise can distort the results of monitoring.
