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REPORTING DATA. DARYL BOWMAN NORTH CAROLINA STATE UNIVERSITY. BIASES IN USING ARITHMETIC MEANS. HIGHER-YIELDING SITES HAVE A BIGGER INFLUENCE ON ACROSS SITE MEANS MEASURING VARIANCES OF YIELD ACROSS SITES RESULTS IN A MEASURE OF BIOLOGICAL STABILITY NOT AGRONOMIC STABILITY.
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REPORTING DATA DARYL BOWMAN NORTH CAROLINA STATE UNIVERSITY
BIASES IN USING ARITHMETIC MEANS • HIGHER-YIELDING SITES HAVE A BIGGER INFLUENCE ON ACROSS SITE MEANS • MEASURING VARIANCES OF YIELD ACROSS SITES RESULTS IN A MEASURE OF BIOLOGICAL STABILITY NOT AGRONOMIC STABILITY
RELATIVE YIELD AS A MEASURE OF ENTRY PERFORMANCE IN VARIABLE ENVIRONMENTS S.K. YAU AND J. HAMBLIN. CROP SCI. 34:813-817
RELATIVE YIELD • MEAN YIELD OF AN ENTRY EXPRESSED AS A PERCENTAGE OF THE MEAN YIELD AT THAT SITE • MEAN RELATIVE YIELD IS THE AVERAGE OF INDIVIDUAL RELATIVE YIELDS ACROSS SITES • THE VARIANCE OF AN ENTRY RELATIVE YIELD THEN BECOMES A MEASURE OF AGRONOMIC STABILITY
ADVANTAGES OF USING RELATIVE YIELD • ONE CAN MEASURE AGRONOMIC STABILITY • GIVES EQUAL WEIGHT TO EACH SITE • ALLOWS COMPARISON AMONG ENTRIES IN DIFFERENT EXPERIMENTS
BIAS TO HIGH-YIELDING SITES USING ARITHMETIC MEANS IS LARGE WHEN INDIVIDUAL SITE MEANS DIFFER GREATLY AND ONLY A FEW SITES ARE USED BUT MAY BE TOLERABLE IF RANGE OF SITE MEANS IS SMALL • D.G. PEDERSON. 1986. EFFECTS OF LOGARITHMIC AND SITE MEAN TRANSFORMATIONS ON THE RELATIVE YIELDS FROM A VARIETY TRIAL. EUPHYTICA 35:169-174.
UNCONSCIOUS BIAS AGAINST LOW-YIELDING SITES BY USE OF ARITHMETIC MEANS COULD HAVE THE SAME EFFECT AS DELIBERATELY EXCLUDING STRESSFUL LOW-YIELDING SITES OR ONLY CONDUCTING HIGH-YIELDING SITES YAU AND HAMBLIN 1994
LOW-YIELDING SITES SHOULD NOT BE EXCLUDED FROM THE ANALYSIS P.E. HILDEBRAND. 1990. MODIFIED STABILITY ANALYSIS AND ON-FARM RESEARCH TO BREED SPECIFIC ADAPTABILITY FOR ECOLOGICAL DIVERSITY. P. 169-180. IN. M.S. KANG (ed.) GENOTYPE-BY-ENVIRONMENT INTERACTION AND PLANT BREEDING.
SITES WITH LARGE DIFFERENCES IN ENTRY PERFORMANCE WITHIN SITES TEND TO HAVE A LARGE INFLUENCE ON MEAN RELATIVE YIELD YAU AND HAMBLIN 1994
WITH MULTIPLE SITES ACROSS VARYING ENVIRONMENTS THE IMPACT OF A LOW-YIELDING SITE OR A SITE WITH LARGE GENOTYPIC VARIANCE SHOULD HAVE MINIMAL IMPACT ON THE FINAL ANALYSIS. UNPUBLISHED STUDIES ON THE IMPACT OF DISCARDING LOW-YIELDING SITES SHOWED THAT REMOVING THEM HOWEVER REDUCED PREDICTABILITY (HOW THE ENTRIES WOULD PERFORM THE NEXT YEAR) DARYL BOWMAN