This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 Excerpt: ...the number of replications, if no check plots were used. As doubling the number of replications will in general give a standard deviation about equal to the original standard deviation divided by the square root of 2, it will reduce variability about 30 %---7071. If alternat ing with check plots will consistently ...
Read More
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 Excerpt: ...the number of replications, if no check plots were used. As doubling the number of replications will in general give a standard deviation about equal to the original standard deviation divided by the square root of 2, it will reduce variability about 30 %---7071. If alternat ing with check plots will consistently reduce variability more than 30 per cent it will be generally a more economical way to control error. Similarly, the use of check plots in every third plot requires as much land as would be required by increasing the number of replications by 50 per cent (using three replications instead of two, or fifteen instead of ten). From this relation the reduction of variability necessary if this practice is to equal replication in effectiveness can be easily computed. Such determinations for check plots at various intervals are shown in Table 30. Table 30.--Reduction Of Variability By The Use Of Check Plots Equivalent To That Probably Attainable With The Same Number Of Plots By Replication. Reduction in standard deviation to If protected single-row or 3-row plots are used in preliminary experiments a more reliable measure of soil productivity is available, and consequently the adjustment of yields is more likely to be of value, than when unprotected single-row plots are used. By the use of planting plans of the sort employed in these experiments, it is possible to adjust the yields by a somewhat shortened method. If adjustment of yield is effective in reducing plot variability in this sort of test it can be accomplished with but little increase in labor. In each of the tests reported in this paper a trial of the effectiveness of adjusting yields by means of check plots was made, the criterion of accuracy being in each case the variability of the yields of ...
Read Less
