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United States Department of Agriculture

Agricultural Research Service

Title: Regression of Forage Yield Against a Growth Index As a Tool for Interpretation of Multiple Harvest Data

Author
item Pedersen, Jeffrey

Submitted to: Haworth Press
Publication Type: Other
Publication Acceptance Date: July 9, 2001
Publication Date: January 7, 2003
Citation: PEDERSEN, J.F. REGRESSION OF FORAGE YIELD AGAINST A GROWTH INDEX AS A TOOL FOR INTERPRETATION OF MULTIPLE HARVEST DATA. HAWORTH PRESS. 2003.

Interpretive Summary: Forage cultivars are often evaluated using multiple harvests throughout one or more growing seasons, and data summarized by presenting a yearly total yield for each cultivar in addition to the yield for each harvest date. Such data summarization becomes difficult to interpret as numbers of entries increase. Regressing yield against a growth index associated with harvest dates can be utilized to describe forage performance in a concise and easily interpreted format. A SAS program is provided that regresses yield of a cultivar against an index calculated as the mean of all entries at a harvest date minus the grand mean. The resulting regression coefficient describes cultivar yield response over several harvests and is indicative of performance under variable growth conditions.

Technical Abstract: Forage cultivars are often evaluated using multiple harvests throughout one or more growing seasons, and data summarized by presenting a yearly total yield for each cultivar in addition to the yield for each harvest date. Such data summarization becomes difficult to interpret as numbers of entries increase. Regressing yield against a growth index associated with harvest dates can be utilized to describe forage performance in a concise and easily interpreted format. A SAS program is provided that regresses yield of a cultivar against an index calculated as the mean of all entries at a harvest date minus the grand mean. The resulting regression coefficient describes cultivar yield response over several harvests and is indicative of performance under variable growth conditions.

Last Modified: 7/30/2014
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