Full TGIF Record # 70963
Item 1 of 1
Publication Type:
Content Type:Abstract or Summary only
Author(s):Van Santen, E.; Guertal, E. A.
Author Affiliation:Auburn University
Title:Are you my neighbor: Re-interpreting NTEP trials with NNA methodology
Section:Turfgrass science
Other records with the "Turfgrass science" Section
Meeting Info.:Minneapolis, MN: November 5-9, 2000
Source:2000 Annual Meeting Abstracts [ASA/CSSA/SSSA]. 2000, p. 155.
Publishing Information:[Madison, WI]: American Society of Agronomy, Crop Science Society of America, Soil Science Society of America
# of Pages:1
Keywords:TIC Keywords: National Turfgrass Evaluation Program; Analytical methods; Relationships; Correlation; Variety trials
Abstract/Contents:"Spatial correlations among plots have been shown to influence the precision of trials. This correlation may be caused by physical relationship among plots as well as temporal relationships during visual quality or color ratings. Nearest neighbor analysis (NNA) can improve the precision of estimates obtained from trials in which spatial correlation is present. We reanalyzed turf quality ratings from eight and five locations, respectively, of the 1990 perennial ryegrass and Kentucky bluegrass trials conducted as part of the National Turfgrass Evaluation Program. Each trial had at least 99 entries, which were replicated three times in a RCB arrangement. The relative efficiency of NNA trials compared to the underlying RCB ranged from 120 to 327%, indicating that the spatial correlation in these trials was very strong. The top ranked 20% of entries in the NNA analysis contained 40-85% of the top ranked entries from the traditional analysis. In six sets of observations belonging to three locations conventional analysis failed to identify the top ranked entry. The NNA adjustments for the bottom 20% of the entries were even greater. In 10% of the 105 locations x rating combinations evaluated the RCB analysis identified fewer than 15% of the bottom 20% of the entries. These large changes in rank at the bottom were most prevalent for the perennial ryegrass trials."
Note:This item is an abstract only!
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Van Santen, E., and E. A. Guertal. 2000. Are you my neighbor: Re-interpreting NTEP trials with NNA methodology. Annu. Meet. Abstr. p. 155.
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