Transformed-response variances fenvalerate data

Table I. Comparison of Transformed Response Variances for Several Powers of Transformation. Fenvalerate Data on the Electron Capture Detector.

The various Datasets A-F were all of fenvalerate. We chose to transform the response values of these sets to the same power as required for the fenvalerate data set since we wished to use these data sets as examples of "unknown" data sets or as examples of poor quality standard sets. If the compound has an inherent analysis quality relating to the response variance, the quality of the poor sets is reflected in differences in the error bands. The acceptable ranges for the Datasets A-F, as shown in Table V, did include the 0.13 power eventually used in all cases where an acceptable H value was found. 

Differences in calibration graph results were found in amount and amount interval estimations in the use of three common data sets of the chemical pesticide fenvalerate by the individual methods of three researchers. Differences in the methods included constant variance treatments by weighting or transforming response values. Linear single and multiple curve functions and cubic spline functions were used to fit the data. Amount differences were found between three hand plotted methods and between the hand plotted and three different statistical regression line methods. Significant differences in the calculated amount interval estimates were found with the cubic spline function due to its limited scope of inference. Smaller differences were produced by the use of local versus global variance estimators and a simple Bonferroni adjustment. 

Response Transformation. Step 1. We found that the calibration graph response data obtained from gas chromatography seldom have constant variance along the length of the graph. The data in Tables I-III clearly show that the larger the response value the larger the variance of the response at that level. Fenvalerate in Table I, chlordecone (kepone) in Table II and chlorothalonil in Table III have the information for untreated data (at a... 

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