The effective use of secondary data

In primary data analysis the individuals who collect the data also analyze it; for meta-analysis an investigator quantitatively combines the statistical results from multiple studies of a phenomenon to reach a conclusion; in secondary data analysis individuals who were not involved in the collection of the data analyze the data. Secondary data analysis may be based on the published data or it may be based on the original data. Most studies of animal cognition involve primary data analysis; it was difficult to identify any that were based on meta-analysis; secondary data analysis based on published data has been used effectively, and examples are given from the research of John Gibbon on scalar timing theory. Secondary data analysis can also be based on the original data if the original data are available in an archive. Such an archive in the field of animal cognition is feasible and desirable. (C) 2002 Elsevier Science (USA).