Stat 405 Lab 4 Randomized completely Block designRCBD
Stat 405 Lab # 4 Randomized completely Block design(RCBD)
The interested model: In this design we are interested in comparing t treatment by using b blocks. •
Hypothesis:
Analysis using spss: To analyze the above model we must to do the following steps: 1) Enter data 2) Describe the data 3) Check on the assumptions: Normality ( plot, kolomogorav sermanove) Constant variance (plot , leven’s test) Note: if the above assumptions are satisfied then we will go to the following steps: 4) Construct the ANOVA table by Analyze > General Linear Model > Univariate >
Decision 5 - Decide if the hypothesis reject or accept based on: F-test (if , then we reject)
OR Based on P-value if P-value < 0. 05, reject null hypothesis. Comment: we conclude that the treatments means are differs, or the treatments affect On the dependent variable at significance level =0. 05. Note: We can covert RCBD to RCD where (SSE+SSB) in RCBD=SSE in RCD
Example: Consider the following the data? An industrial engineer is conducting an experiment on eye focus time. He is interested in the effect of t he distance of the object from the eye on the focus time. Four different distances are of interest. He has five subjects available for the experiment. Because there may be differences between individuals, he decides to conduct the experiment in a randomized block design. The data obtained are shown below?
Subject Distances (Treatments) 4 10 6 6 6 7 6 6 1 6 8 5 3 3 2 5 10 6 4 4 2 3 1) Are there differences in the age focus time for four distances, use State the hypothesis Comment? 2) Does RCBD appear to be appropriate? Why?
Enter data Response Treatment Block
Solution Levene's Test of Equality of Error Variancesa Dependent Variable: focus F df 1. df 2 19 Sig. 0 . Tests the null hypothesis that the error variance of the dependent variable is equal across groups. a. Design: Intercept + Distances + Subject Tests of Normality Kolmogorov-Smirnova Statistic focus . 207 df Sig. 20 . 024 a. Lilliefors Significance Correction Shapiro-Wilk Statistic. 921 df Sig. 20 . 104
Between-Subjects Factors N Distances Subject 4 5 6 5 8 5 10 5 1 4 2 4 3 4 Source 4 4 Corrected Model 69. 250 a 7 9. 893 7. 759 . 001 5 4 Intercept 470. 450 1 470. 450 368. 980 . 000 Distances 32. 950 3 10. 983 8. 614 . 003 Subject 36. 300 4 9. 075 7. 118 . 004 Error 15. 300 12 1. 275 Total 555. 000 20 84. 550 19 Tests of Between-Subjects Effects Dependent Variable: focus Type III Sum of Corrected Total Squares a. R Squared =. 819 (Adjusted R Squared =. 713) df Mean Square F Sig.
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