To manage and conserve natural ecosystems, it is essential to know how biodiversity changes. As one of those questions, it is important to know whether we are we gaining or loosing species. However, getting reliable measurements to study this is a complex task. Data can be collected by researchers during field trips, but a vast amount of data is also provided by different initiatives such as citizen science programs. However, to ensure measurements are reliable, samples need to be representative of the real world. If samples are not representative, they are biased.
In their study, scientists from iDiv, UL and MLU showed that a bias can dramatically change the measurements of biodiversity change. They focused on the so-called site-selection bias, where sampling sites are not selected representatively. For example, if a person wanted to find out how the number of butterfly species is changing in the area over the next