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Assumptions of Variance Analysis
12/2/2018 By Rudi HM
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Assumptions: All population have homogenous variance
Mean and variance are independent eij ~ independent N(0, 1) Block and treatment effects are additive, i.e. no interaction between treatments and block 12/2/2018 By Rudi HM
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Homogenity of variance
t test 2i homogen combined = 2p Analysis of varian => MSError = 2pooled How to detect the homogenity of variance > two population? F test? 12/2/2018 By Rudi HM
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If the variance not equal?
Heterogeneous error variances pose much more serious problem than non normality of the error variances. If ignore the unequal variances and calculate the same F or t test ? The usual test are quite good if: sampel size are all equal larger sample sizes with larger variances. Conclusion will be bias 12/2/2018 By Rudi HM
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Hartley’s Test (homogenity of var.)
Variance of samples: 21, 22, 23,…, 2t F max =H = Percentile of H statistic distribution H table=H((1-);t,r) or Percentage points of the maximum F ratio F(; k; dfmax) k, t=number of treatment r= replication 12/2/2018 By Rudi HM
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The Variance are homogenous
Example 1 A research used four teatments, each treatments were repeated 10 time. The variance of each treatment as follow: 21=193, 22=146, 23= 215, and 24=128 Answer: Ho = 21= 22= 23= 24 H1= Not all 2 homogenous =0.05 => H(0.95;4;10)=6.31 F max= Conclusion: The Variance are homogenous 12/2/2018 By Rudi HM
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Example Data about time required for production of component of car in a plant with three shift. The employee in each shift: 20, 17, 21 person. What is the all variance homogenous? Shift 2i 1 415 2 698 3 384 12/2/2018 By Rudi HM
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BARTLETT’S TEST (homogenity of variance)
If 21, 22, 23,…,2t of r normal population MSE (Aritmatic MSE)= Geometric MSE = GMSE MSE If 21 = 22= 23=…=2t GMSE = MSE 12/2/2018 By Rudi HM
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Log MSE/GMSE 2 , df =t-1 B= 2 = 12/2/2018
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Example Data about time required for production of component of car in a plant with three shift. The employee in each shift: 20, 17, 21 person. What is the all variance homogenous? Shift σ2i 1 415 2 698 3 384 12/2/2018
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2(95%;3-1)=5.99 Conclusion: All varian are homogenous
Shift 2i ri-1 (ri-1) 2i Log 2i (ri-1)log 2i 1 415 19 7885 2.618 49.74 2 698 16 11168 2.843 45.50 3 384 20 7680 2.584 51.68 55 26733 146.92 MSE= Log MSE=2.686 2(95%;3-1)= Conclusion: All varian are homogenous 12/2/2018 By Rudi HM
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Levene’s test Proposed doing a one way analysis of variance on the variables eij=|Yij-Yi| In Two way clasification : Analysis of variance for eij by design of original data If the F-statistic is significant Maap: Ho rejected (Not all variances homogenous) 12/2/2018 By Rudi HM
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Steps of Box’s test The sample corresponding to each treatment group is partitioned into subsamples (equal size and random) The variance of each sample is determined logs of variances One way analysis variance on log of variance If F-statistic is significant homogenity of variance is rejected 12/2/2018 By Rudi HM
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TEST of NORMALITY ij~N(0,1) ? 2 test Lilliefors test 12/2/2018
By Rudi HM
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Step of 2 test for normality
Make the frequency distribution of data Determined: the number of data include in each classes Determined: mean and variance Upper and lower level of each classes are standardized Probability of each classes? Expected frequency of each classes? 2 test: Observed and expected significant difference? H0: ij~N H1: Data distribution not normal 12/2/2018 By Rudi HM
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2 test Example: The telephone number drawn randomly as follow: 23 24 27 29 31 32 33 35 36 37 40 42 43 44 45 48 54 56 57 58 59 61 62 63 64 65 66 68 70 73 74 75 77 81 87 89 93 97 Ho: normal distribution H1: distribution not normal 12/2/2018 By Rudi HM
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Step: 1. Made the frequency distribution Data grouped into classes:
2. Mean? Variance? Class Frequency 20-40 12 40-60 18 60-80 15 80-100 5 50 12/2/2018 By Rudi HM
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3. Standardized upper and lower level
Class Xp=(Xi-X)/ F(Xp) P* 20-40 -1.88 (~) -0.813 0.21 40-60 0.256 0.60 0.39 60-80 1.33 0.91 0.31 80-100 2.4 1 0.09 Class Expected (Ei) Observed (Oi) P* (Ei-Oi)2/Ei <40 0.21x50=10.5 12 0.21 0,214 40-60 0.39x50=19.5 18 0.39 0,115 60-80 0.31x50=15.5 15 0.31 0,016 >100 0.09x50=4.5 5 0.09 0,056 0,401 2tabel= (0,05;4-1-2)= Data normally distribute 12/2/2018 By Rudi HM
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Lilliefor’s Test (Harus diperbaiki)
Draw a graph of the standard normal distribution function (F*(x)) and also empirical distribution function of normalized sample (Zi) Find the maximum vertical distance between two graph F*(x) and S(x) Srandardized data= F(Zi)=P(Z<Zi) S(x)=Number of value Xi Total data 12/2/2018 By Rudi HM
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Frequency Distribution
|F*(x)-S(x)| |F*(x)-S(x)| > Liliefor’s frequency distribution 12/2/2018 By Rudi HM
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Lilliefor’s test Normal distribution Xi Zi F(Zi) S(Zi)
Lo=|F(Zi)-S(Zi)| 23 -1.65 0.0495 0.088 0.0338 27 -1.41 0.0793 0.1667 0.0874 33 -1.05 0.1469 0.2500 0.1031 40 -0.62 0.2676 0.3333 0.0657 48 -0.14 0.4443 0.500 0.0557 57 0.40 0.6554 0.5833 0.0721 59 0.53 0.7019 0.6667 0.0352 62 0.71 0.7612 0.7500 0.0112 68 1.07 0.8577 0.8333 0.0244 69 1.13 0.8708 0.9167 0.0459 70 1.19 0.8830 1 0.1170 X=50.3 , =16.55 12/2/2018 By Rudi HM L max < L tabel=L(0.05;12) Normal distribution
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NON ADITIVITY TEST SS residual=SS error- SSNA SS error= eij2
Ho: = 0 H1: 0 12/2/2018 By Rudi HM
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Anova Source of Variance df SS MS F calc F table Block (r-1) SSB MSB
MSB/MSE Treatment (t-1) SST MST MST/MSE Error (r-1)(t-1) SSE MSE NA 1 SSNA MSNA MSNA/MSPE Pure error [(r-1)(t-1)]-1 SSPE MSPE Total rt-1 12/2/2018
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i j Xij m di bJ eij di2 bJ2 dibjYij 7,41 1 18 10 4 2 16 144 13 -1 -52
-52 3 11 -2 -44 14 8 -3 9 -48 24 5 15 7 -20 12 S ( ….) 160 104 34 S( …..)2 1762 1600 SSNA = 7,41 TSS CF SST SSB SSE SS residu= 26,59 12/2/2018 By Rudi HM
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12/2/2018 By Rudi HM
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Dependent Variable: PROTEIN
Source DF Sum of Squares Mean Square F Value Pr > F BLOCK TREAT Error NA Residual Corrected Total F(0.05; 1; 8)=5.319 12/2/2018 By Rudi HM
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