Multivariate statistics applied to the evaluation of environmental and chemical data sources

Constantly expanding chemical and environmental information sources increase the need for descriptive statistical analysis. This paper gives a comparative evaluation of data sources, i.e. online databases, databases on CD‐ROM and Internet resources in the field of environmental chemicals. The evaluation is based on information in three metadatabases for environmental chemicals: DADB‐Metadatabase of Online Databases, DACD‐Metadatabase of CD‐ROMs, DAIN‐Metadatabase of Internet Resources. A data matrix of 50 environmental and chemical descriptors found in DADB, DACD and DAIN is analysed and a technique is applied to transform the data set into a data matrix of a more homogeneous structure. This method is based on algorithms for solving the so‐called travelling salesman problem. Two different ways of analysing the data set are applied and the results are compared. Also, media combination patterns are identified and discussed. For most descriptors the information depth is higher in commercial online databases and databases on CD‐ROM than in free Internet resources. Exceptions, e.g. some health‐related parameters which have a higher percentage in Internet resources, are identified and explained.