Mathematics Colloquium



Department of Mathematics
University of Nebraska at Omaha


WHEN:
Thursday, January 20, 2005 at 2:30 PM

WHERE:
Durham Science Center, Room 255

WHAT:


Trisha Hooks

Faculty Candidate


will give a talk on

Unreplicated Variety Trials: Effects of Check Plot Density and Fixed Versus Random Treatments


ABSTRACT:
Crop researchers performing germplasm screenings are often unable to replicate their plots due to scarcity of seed and the large numbers of genotypes being evaluated. The incorporation of known "check" varieties is a common method of overcoming the difficulties associated with unreplicated trials. However, the researcher who chooses to use an unreplicated design must decide on the number of checks to include in the study (i.e., check plot density) and whether to regard treatment as a fixed or random effect. In this simulation study, we explore the effects of check plot density on the efficiency of the resulting analysis. We also explore the effect of analyzing treatments as random versus fixed. Our study considers ten different designs with check densities ranging from 5% to 50%. The designs and analyses are then compared on the basis of the correlation of the actual treatment effects with each of the following: "observed" yield, least square means (LSMEANs) for fixed treatments, and best linear unbiased predictors (BLUPs) for random treatments. Finally, we observe the frequency with which the analysis ranks the top 10% of the treatments within the top 15% of the LSMEANs or BLUPs.


[Back]    Back to the Mathematics Colloquium Page