Understanding VecDyn error flags for re-digitized data
Please note this is a draft as we prepare for our next site update.
When importing historical population abundance records from graphs into the VecDyn database, curators may encounter scenarios that results in data imported that is less exact than when data is received in tabular records.
We have therefore devised three warning ‘flags’ to highlight this uncertainty so data users are aware and proceed with data analysis appropriately. In this post, we explain and provide examples of each issue and the corresponding warning flag.
In the data upload and download, a value of “TRUE” means the indicated issue may exist, and a warning flag will appear in the data explorer.
digitized_from_graph
True if for data that has been digitized from a graph. This method introduces error. Frequently, the y-axis (abundance) is likely to be affected as any determination in the above example of the y-axis value is clearly an approximation.
time_shift_possible
True if the digitizer reports that the entire time axis may be shifted earlier or later from actual values. This is most likely a consequence of an unclear axis labels or markings. In this example, it is not clear which point actually represents the 10/98 collection, or which days within October the collection was made.
date_uncertainty_due_to_graph
True if the digitizer felt it was difficult to ascertain the correct date of any given recording (while interpreting a graph.) While this can be subjective, this warning may be used, when irregular sampling frequencies or a high density of values along a x-axis make interpretation difficult.
