Abundance Anomaly

The abundance anomaly calculator estimates the percent change in arthropod abundance for a target year compared to the previous 5-year average abundance for the same time period. This can help track arthropod activity in an area over time and between agencies.

Fields

  • Agency: Choose the agency or agencies for which you wish to calculate an abundance anomaly. Multiple agencies can be selected by using the CTRL/CMD/SHIFT keys while selecting values. This could be your own agency to compare the current year to past years, or more than one agency to compare to neighboring districts. If the Treat each selected agency independently box is checked, the abundance anomaly will be stratified by agency (ignored if only one agency is selected). If left unchecked, the abundance anomaly will be aggregated for all selected agencies.
  • Year: This is the year for which you wish to calculate an abundance anomaly. This year’s abundance at the desired time interval will be compared to the average abundance from the previous 5 years.
  • Time Interval: How frequently should the abundance anomaly be calculated? There are several built-in options, or you can manually specify a date range within the selected year. Date format is based on the settings under Account Preferences.
  • Spatial Filter: This feature allows you to filter results within the agency or agencies. You can draw a polygon on the map using the feature tab, or include a previously saved feature from the Spatial Features page. Polygon example Alternatively, you can filter by site group, region (determined when creating a new site), or specific site. For these filters, multiple values can be selected by using the CTRL/CMD/SHIFT keys while selecting values. If the Treat each selected filter independently box is checked, the abundance anomaly will be stratified by spatial filter, otherwise abundance will be aggregated for the selection. If the “All Available…” option is selected or no feature polygon(s) is provided, any calculation(s) will not use spatial filters.
  • Species: Here you can choose whether to look at the abundance anomaly for all species or selected species of interest. Multiple species can be selected by using the CTRL/CMD/SHIFT keys while selecting values. If the Treat each selected species independently box is checked, the abundance anomaly will be stratified by species, otherwise abundance will be aggregated for all selected species.
  • Sex/Condition: Typically, females of various conditions are of interest when calculating the abundance anomaly, but you could also examine males, unknown sex, eggs, larvae, and pupae. Multiple values can be selected by using the CTRL/CMD/SHIFT keys while selecting values, and checking the Treat each selected sex/condition individually box will stratify the abundance anomaly by the selected values.
  • Trap Type: Filter the results by the trap type used for the collection. This is helpful to ensure that are comparable over time and/or across agencies. Similar to Sex/Condition, multiple trap types can be selected by using the CTRL/CMD/SHIFT keys while selecting values, and checking the Treat each selected trap type individually box will stratify the abundance anomaly by the selected traps.
  • Historical Mean Type: The type of mean when calculating the 5-year average abundance to which the current year’s abundance is compared. The default is a geometric mean, which is appropriate for most situations, but you can also choose the arithmetic mean (average), harmonic mean, or the weighted version of any of these three options.

Results

The # of Calculations indicator shows how many calculations will be performed based on the stratifications (checkboxes) that have been selected. If none of the boxes were checked, abundance at the desired time interval will be aggregated to a single calculation. The resulting table is downloadable, and you also have the option to view a time series graph comparing the current year’s abundance curve to the 5-year average abundance curve.