Some considerations for the further development of statistical summaries of CEMP indices

A potential method is presented for combining data collected as part of the CCAMLR ecosystem monitoring programme (CEMP) into a single index for each of the predator, prey and environment parameters. The proposed method is based on the usual theory of multivariate statistics and takes into account the covariance between parameters. The power of the statistical procedure recently adopted by WG-EMM for identifying anomalies in CEMP parameters is examined by means of simulation tests. The power of the procedure to detect anomalies was found to fall to low levels once more than a few anomalous values have appeared in the data. An alternative procedure, using baseline mean and variance estimates was found to have consistently better statistical power regardless of the accumulation of anomalies. An approach to the further development of CEMP indices is outlined.