TABLE 1.

Summary of the functions provided in occAssess

Function	Type of bias assessed	Method (in brief)	Output	Dataset type	Additional data required
assessEnvBias	Environmental bias. Indicates whether the input data are likely to be sampled from the same portion of environmental space over time, or whether the data are sampled from a representative portion of environmental space in the spatial domain of interest	Reduces the dimensionality of environmental space using principal component analyses and maps the distribution of the data in this reduced environmental space	Maps of the distribution of the data on two user‐selected principal components of environmental space. Displayed as ellipses or points. One ellipse or set of points per period	Single or multispecies. Highly likely to indicate strong bias with one or a small number of species	Environmental data corresponding to each occurrence data point and, optionally, a background sample (e.g. a random sample from the domain of interest for inference)
assessRarityBias	Indicates whether rare species are overrepresented in the data and whether the degree to which they are overrepresented changes over time	Measures the congruence of the number of times species have been recorded and their estimated commonness (range sizes). Drops records not identified to species level	Time series showing congruence in each period (correlation or r 2 from regression of the number of records on commonness)	Multispecies only	None
assessRecordNumber	Identifies temporal variation in sampling intensity in the domain of interest	Sums the number of records in the dataset in each time period	Time series of counts	Single or multispecies	None
assessSpatialBias	Indicates whether the data resemble a random distribution in the geographic space of interest for inference, and whether the extent to which the data resemble a random distribution change over time	Compares the average nearest neighbour distance of the data with the average nearest neighbour distances of simulated random distributions of the same density	Time series showing nearest neighbour index in each period	Single or multispecies. Highly likely to indicate strong bias with one or a small number of species	Raster layer indicating which areas fall inside the study extent
assessSpatialCov	Indicates whether a representative portion of the spatial domain of interest has been sampled and whether the same portion of geographic space has been sampled over time	Maps the data in geographical space	Either multiple (gridded) maps showing the distribution of the data in each period, or one map showing the number of periods in which grid cells have been sampled	Single or multispecies	If the input data are not on WGS84 coordinate reference system, then any country or political boundaries that the user requires to be superimposed on the resultant plots must be supplied
assessSpeciesID	Taxonomic resolution and whether it changes over time	Calculates proportions or counts of records identified to species level	Time series of proportions or counts	Multispecies only	None
assessSpeciesNumber	Taxonomic coverage and how it changes over time	Sums the number of species recorded in each time period. Drops records not identified to species level	Time series of counts	Multispecies only	None

Note that users can opt to split the data into multiple time periods; in this case all functions are temporally explicit and hence provide information on temporal variation in some characteristic of the data. See the worked example in the main text for more details of each function.