Tag Archives: sampling bias

Not All Datasets Are Created Equal

Image Credit: Chinmaysk, CC BY-SA 3.0, Image Cropped

Species data for understanding biodiversity dynamics: The what, where and when of species occurrence data collection (2021) Petersen et al., Ecological Solutions and Evidence, https://doi.org/10.1002/2688-8319.12048

The Crux

With the rise of the internet, GPS’ and smartphones, the amount of openly available species occurrence data has reached previously unfathomable numbers. This increase is mostly due to the engagement of the citizen scientist – regular people getting out there in nature and taking part in data collection and research. From people taking photos of flowers in their backyard to organised salamander spotting safaris, citizen scientists have opened up data that previously would have cost massive amounts to produce.

The Global Biodiversity Information Facility (GBIF) is the largest hub of such data, collating data ranging from amateur observation to museum specimens to professional surveys. It is well-known, however, that this kind of openly available data comes with a myriad of caveats: some species groups are reported much more than others (I am looking at you, bird-watchers), and “roadside bias” (see Did You Know?) haunts the records. But how are the records distributed among different land-cover types on a country-scale, does it differ between groups of conservation concern, and does it depend on who the reporters are?

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It’s All Relative: Measuring Abundance In The Face of Detection Bias

There are many papers out there discussing estimates of abundance and occurrence of a variety of plants and animals. Sometimes you’ll also see references to relative abundance and relative occurrence. What makes researchers go for one estimate over the other? When might you face a similar choice? The goal of this post is to try to shed some light on when you might want to keep things relative.

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