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| Stevens,W. L.. |
| This paper describes the statistical analysis of a varietal trial with two unusual characteristics : (i) The plant (coffee) is one of those which show strong maxima and minima of production in alternate years. This phenomenon must be prevented from masking or biasing the other varietal comparisons in which we are interested. (ii) The design of the experiment is systematic. It was laid down in Campinas, Brazil, in 1933 at a time when the principles of randomisation were not so widely known as they are today. THE EXPERIMENT AND DATA. Six varieties are compared, denoted by A B C D E and F (see page 104). They are planted in thirty rows, each with 50 plants, according to the systematic design : A B C D E F A B C D E F A B C D E F A B C D E F A B C D E F Data... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1949 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87051949000200002 |
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| Stevens,W. L.; Fraga Jr.,C. G.. |
| This paper was written primarily to illustrate the process of fitting constants to non-orthogonal data. The design of the experiment, on the pruning of lower branches of coffee-trees, was systematic (see plan at the beginning). Three constants were fitted, representing respectively the treatment contrast, the difference between upper and lower half of the field and the linear gradient of fertility across the field. The use of the residual sum of squares for the estimation of error is not, of course, logically correct but it is unlikely to lead to seriously wrong conclusions if caution is exercised. In the event, the procedure failed to eliminate any soil heterogeneity (see Analysis of Variance, p. 288). Inspection of the data showed that much of the... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1951 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87051951000400003 |
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