1.3 Biotic data: summary stats

To show the utility of this tool, we will calculate some summary statistics from a study examining changes in macrofaunal communities inhabiting sediments near an oil platform (Ekofisk) in the North Sea, provided by Gray et al. (1990) . These data consist of counts of the abundances of $p$ = 174 taxa (mostly identified to species level) sampled by 3 day grabs taken at each of $N$ = 39 stations, situated in an approximately 5-spoke radial design leading out from the oil platform. The stations were classified into the following four groups according to their relative distance from the centre of drilling activity at the Ekofisk oil platform: D = less than 250m, C = 250m - 1km, B = 1 - 3.5km, and A = more than 3.5km away.

Start running PRIMER 8, then click File > Open... to open the data file named 'Ekofisk_macrofauna_counts.pri' (found inside the 'Examples_P8 > Ekofisk_macrofauna' folder).

From the 'Ekofisk_macrofauna_counts' data sheet inside PRIMER, click on Tools > Summary Stats..., as shown below:

Choose from the dialog all of the summary statistics you would like to calculate on the dataset. For example, we might choose to calculate the average, median, minimum, maximum, range, standard deviation, number of zeros, singletons, and the number of non-zeros (i.e., frequency of occurrence), like this:

Click 'OK', and you will see a 'Summary Statistics 1' file, in which you are shown the choices you made for running that routine, viz:

as well as a resulting output file 'Data1', which provides all of these summary statistics for each of the individual variables (taxa), as shown below: