Full TGIF Record # 63258
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Publication Type:
Content Type:Abstract or Summary only
Author(s):Karcher, D. E.; Schabenberger, O.; Rieke, P. E.; Nikolai, T. A.; Rogers, J. N. III
Author Affiliation:Michigan State University
Title:Rating data: Reporting results in a statistically valid manner
Section:Turfgrass science
Other records with the "Turfgrass science" Section
Meeting Info.:Salt Lake City, UT: October 31 - November 4, 1999
Source:1999 Annual Meeting Abstracts [ASA/CSSA/SSSA]. Vol. 91, 1999, p. 131.
Publishing Information:[Madison, WI]: American Society of Agronomy, Crop Science Society of America, Soil Science Society of America
# of Pages:1
Keywords:TIC Keywords: Quality; Measurement; Models; Turfgrass quality; Comparisons; Quality evaluation
Abstract/Contents:"Objectives of turfgrass research often require evaluation of turf quality. Turf quality is composed of several factors (color, density, uniformity, and texture) making quantification difficult. Evaluations typically involve assigning scores to turf plots using a scale of 1 to 9. Scores have traditionally been analyzed as continuous data, using ANOVA techniques to test hypotheses of treatment equality. These data are actually discrete (ordinal), and violate assumptions required for ANOVA. The proportional odds model (POM) accounts for the multivariate distribution of quality data. The POM estimates treatment parameters and predicts cumulative probability distributions (i.e. the probability of treatment #2 to receive a rating of "4"). The POM offers appropriate and powerful treatment comparisons and the results are independent of the category scores. Example data analyses using macros developed by the authors will be discussed."
Note:This item is an abstract only!
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Karcher, D. E., O. Schabenberger, P. E. Rieke, T. A. Nikolai, and J. N. III Rogers. 1999. Rating data: Reporting results in a statistically valid manner. Annu. Meet. Abstr. 91:p. 131.
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