l6 - STAT 350 Fall 2008 Lab#6 Solution For the following...

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STAT 350 – Fall 2008 Lab #6 Solution For the following problems, do the analysis using SAS. Please put all SAS input (Editor window) and all SAS output (Output window, NOT the Log window) as an appendix. Nothing pasted directly from SAS should be given as an answer to the questions below! 1. Four formulations of fertilizer (called A, B, C, and D) were tested for their effect on corn yield. Each fertilizer was applied to 15 individual 1-acre plots and corn yield (in bushels) was measures. The data is given in the associated Excel file on the "fertilizer" worksheet. Conduct an analysis of variance on this data. If appropriate also conduct an appropriate multiple comparison test to determine if any of the fertilizers result in significantly different yields. a. Present a nice table summarizing the data: the mean and standard deviation of the yields for each fertilizer. Fertilizer Mean Standard Deviation A 140.800 14.145 B 153.085 15.483 C 159.295 11.816 D 146.750 12.085 b. Give an ANOVA table to summarize the ANOVA results. Make a nice table (as you would do for a report/publication) – do NOT paste in anything from SAS directly! Source df Sums of Squares Mean Squares F p Fertilizer 3 3822.31 1274.10 7.02 0.0003 Error 76 13784.49 181.37 Total 79 17606.80 c. What is the p -value for the ANOVA? State the null hypothesis you are testing and state what your conclusion about this hypothesis is. The p -value is 0.0003. The null hypothesis is that the mean yield of corn is the same for all 4 fertilizers. Clearly we will be rejecting that null hypothesis and concluding that at least one of the fertilizers results in a yield that is significantly different from the others. Lab #6 - Solution Page 1 of 10
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d. If appropriate, present the results of the multiple comparison test using the line-method discussed in class. In a few sentences, clearly explain what these results mean (assume you are talking to a farmer/biologist who is not up on his statistical jargon). In this case, Tukey's test is appropriate (we have no "control"). Fertilizer C Fertilizer B Fertilizer D Fertilizer A 159.295 153.085 146.750 140.800 Fertilizer C resulted in the highest mean yield, but this was not significantly different than Fertilizer B. There was no statistically significant difference in the mean yields of Fertilizer B and Fertilizer D. Fertilizer A resulted in the lowest mean yield, but this was not significantly different from Fertilizer D. 2.
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This note was uploaded on 02/23/2009 for the course STAT 350 taught by Professor Staff during the Fall '08 term at Purdue.

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l6 - STAT 350 Fall 2008 Lab#6 Solution For the following...

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