Validation of a ferritin assay

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Description

For each of seven periods in which there was a new batch of reagent, a small set of patient samples was assayed for ferritin content using both the old and new batches.

Usage

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Format

A data frame with 162 observations on the following 4 variables.

sample

sample identifier

period

the transition number, 1 to 7

old.lot

assay result using the old lot of the reagent

new.lot

assay result using the new lot

Details

The samples from each period are distinct. In the second data set ferritin2 outliers have been added to the data for period 2, excess noise added to one lot in period 4, and deterministic laboratory error to period 6.

Source

Blinded data from a clinical laboratory.

Examples

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data(ferritin)
temp <- ferritin[ferritin$period <4,]
plot(temp$old.lot, temp$new.lot, type='n', log='xy',
     xlab="Old lot", ylab="New Lot")
text(temp$old.lot, temp$new.lot, temp$period,
         col=temp$period)