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Check digits for detecting recording errors in horticultural research: theory and examples

Okie, W.R., Okie, E.G.
HortScience 2005 v.40 no.7 pp. 1956
horticulture, horticultural crops, agricultural research, data analysis, plant breeding, data collection
Check digit technology is frequently used in commercial applications such as shipping labels and credit cards to flag errors in numbers as they are used. Most systems use modular arithmetic to calculate a check digit from the digits in the identification number. Check digits are little used in horticultural research because the guidelines for implementing them are neither well known nor readily accessible. The USDA-ARS stone fruit breeding program at Byron, Ga., plants thousands of trees annually, which are identified using a 2-digit year prefix followed by a sequential number that identifies the tree location in the rows. Various records are taken over the life of the tree including bloom and fruit characteristics. Selected trees are propagated and tested further. To improve the accuracy of our records we have implemented a system which uses a check number which is calculated from the identification number and then converted to a letter that is added onto the end of the identification number. The check letter is calculated by summing the products of each of the digits in the number multiplied by sequential integers, dividing this sum by 23, and converting the remainder into a letter. Adding a single letter suffix is a small change and does not add much complexity to existing data collection. The types of errors caught by this system are discussed, along with those caught by other common check digit systems. Check digit terminology and theory are also covered.