| Popis: |
The statistical analysis of lead isotope ratio data in archaeology has attracted considerable controversy, but one area of consensus seems to be that a minimum sample size of 20 is adequate for the satisfactory characterisation of a lead isotope field. The argument in the present paper is that this is too small. Twenty would be satisfactory if the assumption of normality sometimes used in analysing lead isotope was correct, but it is inadequate for checking this assumption or detecting non-normal structures within a field. Evidence based on both real and simulated data suggests that 40 may be a more realistic minimum, and even this is not always adequate. The consequences of incorrectly assuming normality, and alternative methods of analysis that do not involve this assumption, are investigated. |
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