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# lab 11 - EXST 7005 Fall 2010 Lab#11 Randomized Complete...

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1 EXST 7005 Fall 2010 Lab #11: Randomized Complete Block Design Simple Linear Regression Randomized Complete Block Design A Randomized Complete Block Design (RCBD) is a restricted randomization design in which the experimental units are first sorted into homogeneous groups, called blocks, and the treatments are then assigned at random within the blocks. In a Randomized Complete Block Design, each level of a "treatment" appears once in each block, and each block contains all the treatments. The experimental units are assumed to be homogeneous within each block. Variability coming from the block variable is not of interest to the researcher, so the addition to SSE from variation between the blocks is removed from consideration in the ANOVA table. By doing so, we hope to increase the power of the test. This would allow us to detect smaller differences between treatments. Example: The researchers want to test the effects of three insecticides which are used to protect seedlings. To get a larger sample, they get 4 plots of land with the same seedlings and apply all the three insecticide on each of the plot. After a period, the researcher measures the number of healthy seedlings (per 100 seedlings) on each plot. The researchers are not interested in the difference of plots. They are only interested in the effects of insecticides. Plot 1 Plot 2 Plot 3 Plot 4 Insecticide 1 56 48 66 62 Insecticide 2 83 78 94 93 Insecticide 3 80 72 83 85 title1 'Randomized Complete Block Design' ; data SEEDS; title2 'Analysis of the effects of three insecticides' ; input SEEDLINGS INSECTICIDE PLOT; cards ; 56 1 1 48 1 2 66 1 3 62 1 4 83 2 1 78 2 2 94 2 3 93 2 4 80 3 1 72 3 2 83 3 3 85 3 4 ;

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2 We will use PROC MIXED procedure in which the random effect variable (PLOT) is not included in the MODEL statement. Instead, it goes into the RANDOM statement. Since the AVONA results show that the three insecticides have significantly different effects, we use LSMEANS to find how they differ. The
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## This note was uploaded on 12/29/2011 for the course EXST 7005 taught by Professor Geaghan,j during the Fall '08 term at LSU.

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lab 11 - EXST 7005 Fall 2010 Lab#11 Randomized Complete...

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