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Titolo:
BIAS IN GENETIC VARIANCE ESTIMATES DUE TO SPATIAL AUTOCORRELATION
Autore:
MAGNUSSEN S;
Indirizzi:
FORESTRY CANADA,PETAWAWA NATL FORESTRY INST,GENET GROWTH & YIELD CHALK RIVER K0J 1J0 ON CANADA
Titolo Testata:
Theoretical and Applied Genetics
fascicolo: 2-3, volume: 86, anno: 1993,
pagine: 349 - 355
SICI:
0040-5752(1993)86:2-3<349:BIGVED>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
FIELD EXPERIMENTS; STATISTICAL-ANALYSIS; TRIALS; COMPETITION; MODELS; SELECTION; PLOTS;
Keywords:
GENETIC VARIANCE; EXPERIMENTAL DESIGN; SIMULATION; SPATIAL PROCESS; NEAREST NEIGHBOR ADJUSTMENT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
39
Recensione:
Indirizzi per estratti:
Citazione:
S. Magnussen, "BIAS IN GENETIC VARIANCE ESTIMATES DUE TO SPATIAL AUTOCORRELATION", Theoretical and Applied Genetics, 86(2-3), 1993, pp. 349-355

Abstract

A central problem in the analysis of genetic field trials is the dichotomy of ''genetic'' and ''environmental'' effects because one cannot be defined without the other. Results from 768,000 simulated family trials in complete randomized block designs demonstrated a serious upward bias in estimates of family variance components from multi-unit plotdesigns when the phenotypic observations were compatible with a first-order autoregressive (AR1) process. The inflation of family variancesand, thus, additive genetic variance and narrow sense individual heritabilities progressed exponentially with an increase in the nearest neighbor correlation (theta) in the AR1 process. Significant differencesin inflation rates persisted among various plot configurations. At theta = 0.2 the inflation of family variances reached 48 - 73 %. Inflation rates were independent of the level of heritability. Modified Papadakis nearest-neighbor (NN) adjustment procedures were tested for theirability to remove the bias in family variances. A NN-adjustment basedon Mead's coefficient of inter-plant interaction and one derived fromBartlett's simultaneous autoregressive scheme removed up to 97% of the bias introduced by the phenotypic correlations. NN-adjusted estimates had slightly (5-8%) higher relative errors than did unadjusted estimates.

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Documento generato il 25/11/20 alle ore 18:09:30