ARS | Publication request: IMPACT ON CALVING EASE EVALUATIONS OF MODIFYING OR EXCLUDING DATA FROM HERD-YEARS WITH ABNORMAL DISTRIBUTIONS OF SCORES

Submitted to: World Congress of Genetics Applied in Livestock Production
Publication Type: Proceedings
Publication Acceptance Date: May 6, 2006
Publication Date: August 13, 2006
Citation: Van Tassell, C.P., Wiggans, G.R. 2006. Impact on calving ease evaluations of modifying or excluding data from herd-years with abnormal distributions of scores. 8th World Congress of Genetics Applied in Livestock Production. Communication 01-88.

Interpretive Summary: The effects of combinations of collapsing score categories to force a mode of one and removing records from herd-years with abnormal distributions were studied to determine their effect on increasing the consistency of evaluations over time. Evaluations were calculated for time periods representing current run, previous run, and data with the last four years excluded. Categories based on distribution included all data, data with collapsed categories, and data with approximately one and five percent excluded based on two goodness of fit criteria. Collapsing categories was beneficial across all evaluation criteria. The additional exclusions based on goodness of fit gave inconsistent results. Editing calving ease data to eliminate herd-years with abnormal distributions improves predictability of future evaluations.

Technical Abstract: The effects of combinations of collapsing score categories to force a mode of one and removing records from herd-years with abnormal distributions were studied to determine their effect on increasing the consistency of evaluations over time. Evaluations were calculated for time periods representing current run, previous run, and data with the last four years excluded. Categories based on distribution included all data, data with collapsed categories, and data with approximately one and five percent excluded based on two goodness of fit criteria. Collapsing categories was beneficial across all evaluation criteria. The additional exclusions based on goodness of fit gave inconsistent results. Editing calving ease data to eliminate herd-years with abnormal distributions improves predictability of future evaluations.