Sample variability |
"Laboratory methodology has reached a point where analytical error contributes only a very small portion of the total variance seen in the data. Examination of the results of a components of variance analysis performed on soils data from an NPL site sampled for PCBs indicated that 92% of the total variation came from the location of the sample, while only 8% was introduced after the sample was taken. Less than 1% of the total variance could be attributed to the analytical process itself." From-- Preparation of Soil Sampling Protocols: Sampling Techniques and Strategies. EPA/600/R-92/128, July 1992. |
"Typically, errors in the taking of field samples are much greater than preparation, handling, analytical, and data analysis errors; yet, most of the resources in sampling studies have been devoted to assessing and mitigating laboratory errors. It may be that those errors have traditionally been the easiest to identify, assess and control." From-- A Rationale for the Assessment of Errors in the Sampling of Soils. EPA/600/4-90/013, July 1990. |
Some interesting insights on the issue of sample variability... |
">
">
">
">
">
">
">
">
