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Sampling Issues for Cotman Data Collection

Mark Cochran, Kieth Vodrazka, N. P. Tugwell, Diana Danforth and Sha Mi


 
ABSTRACT

This study was conducted to determine the appropriate sampling design for COTMAN data collections. Design issues focus on the number of sites per field and the number of plants per site that should be sampled. Intensive sampling of 84 commercial fields in Northeast Arkansas (Mississippi County) and 93 commercial fields in east Central Arkansas (Lee and Phillips Counties) were collected in 1995. Data were analyzed for plant height, first position square retention, squaring nodes and nodes above white flower. A nested ANOVA was used to assess the percent contribution of to total variance attributable to sites and to plants per sites. The sample size for a given cost per field that minimized the variance was also calculated. These optimal sample sizes were contrasted with current COTMAN sampling recommendations. With the possible exception of plant height measures, the optimal sample sizes fell within the recommended ranges.



Reprinted from Proceedings of the 1999 Beltwide Cotton Conferences pp. 463 - 464
©National Cotton Council, Memphis TN

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Document last modified Monday, Jun 21 1999