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1 Power Fifteen Analysis of Variance (ANOVA)
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2 Analysis of Variance w One-Way ANOVA Tabular Regression w Two-Way ANOVA Tabular Regression
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3 One-Way ANOVA w Apple Juice Concentrate Example, Data File xm 15-01 w New product w Try 3 different advertising strategies, one in each of three cities City 1: convenience of use City 2: quality of product City 3: price w Record Weekly Sales
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4 Advertising Strategies & Weekly Sales for 20 Weeks
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5 Is There a Significant Difference in Average Sales? Null Hypothesis, H 0 : Alternative Hypothesis: ≠ or ≠ or ≠
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6 F k-1, n-k = [ESS/(k-1)]/[USS/(n-k)]
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7 Apple Juice Concentrate ANOVA F 2, 57 = 28,756.12/8894.45 = 3.23
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8 F-Distribution Test of the Null Hypothesis of No Difference in Mean Sales with Advertising Strategy F 2, 60 (critical) @ 5% =3.15
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9 Regression Set-Up: y(1) is column of 20 sales observations For city 1, 1 is a column of 20 ones, 0 is a column of 20 Zeros. Regression of a quantitative variable on three dummies Y = C(1)*Dummy(city 1) + C(2)*Dummy(city 2) + C(3)*Dummy(city 3) + e
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10 One-Way ANOVA and Regression Regression Coefficients are the City Means; F statistic
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12 Two-Way ANOVA w Apple Juice Concentrate w Two Factors 3 advertising strategies 2 advertising media: TV & Newspapers w 6 cities City 1: convenience on TV City 2: convenience in Newspapers City 3: quality on TV Etc.
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13 Advertising Strategies In Two Media: Weekly Sales
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14 Mean Weekly Sales By Strategy and Medium
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price
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17 Is There Any Difference In Mean Sales Among the Six Cities?
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18 Table of ANOVA for Two-Way
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19 Formulas For Sums of Squares a is the # of treatments for strategies =3 b is the # of treatments for media =2 r is the # of replicates or observations =10 The Grand Mean:
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20 Formulas For Sums of Squares (Cont.) Where the mean for treatment i, strategy, is:
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21 Mean Weekly Sales By Strategy and Medium
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22 Formulas For Sums of Squares (Cont.) Where the mean for treatment j, medium, is:
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23 Formulas For Sums of Squares (Cont.) Where is the mean for each city
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24 Table of Two-Way ANOVA for Apple Juice Sales
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25 F-Distribution Tests Test for Interaction: Test for Advertising Medium: Test for Advertising Strategy:
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26 = Regression Set-Up Convenience dummy Quality dummy TV dummy constant
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SALESAPJCONVENIENCEQUALITYPRICE TELEVISIONNEWSPAPERS 49110010 71210010 55810010 44710010 47910010 62410010 54610010 44410010 58210010 67210010 46410001 55910001 75910001 55710001 52810001 67010001 53410001 65710001 55710001 47410001 67701010 62701010
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Dependent Variable: SALESAPJ Method: Least Squares Sample: 1 60 Included observations: 60 VariableCoefficientStd. Errort-StatisticProb. CONVENIENCE -48.5000043.08204-1.1257590.2652 QUALITY 62.7000043.082041.4553630.1514 TELEVISION -24.4000043.08204-0.5663610.5735 C 624.400030.4636020.496590.0000 CONVENIENCE*TELEVISION 4.00000060.92720 0.065652 0.9479 QUALITY*TELEVISION -19.70000 60.92720 -0.3233370.7477
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R-squared0.184821 Mean dependent var614.3167 Adjusted R-squared0.109342 S.D. dependent var102.0765 S.E. of regression96.33436 Akaike info criterion12.06817 Sum squared resid501136.7 Schwarz criterion12.27760 Log likelihood-356.0450 F-statistic2.448631 Durbin-Watson stat2.452725 Prob(F-statistic)0.045165
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Dependent Variable: SALESAPJ Method: Least Squares Sample: 1 60 Included observations: 60 Variable CoefficientStd. Errort-StatisticProb. CONVENIENCE -46.5000029.96267 -1.5519310.1263 QUALITY 52.8500029.96267 1.7638620.0832 TELEVISION-29.6333324.46441 -1.2112830.2309 C627.016724.4644125.629740.0000 R-squared 0.182203 Mean dependent var614.31 Adjusted R-squared0.138393 S.D. dependent var 102.0765 S.E. of regression 94.75027 Akaike info criterion 12.00471 Sum squared resid 502746.3 Schwarz criterion 12.14433 Log likelihood-356.1412 F-statistic4.158888 Durbin-Watson stat2.456222 Prob(F-statistic) 0.009921
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Dependent Variable: SALESAPJ Method: Least Squares Sample: 1 60 Included observations: 60 VariableCoefficientStd. Errort-StatisticProb. CONVENIENCE -46.5000030.08521-1.5456100.1277 QUALITY52.8500030.085211.7566770.0843 C612.200021.2734628.777650.0000 R-squared0.160777 Mean dependent var614.31 Adjusted R-squared0.131330 S.D. dependent var102.07 S.E. of regression95.13779 Akaike info criterion 11.99724 Sum squared resid515918.3 Schwarz criterion12.101 Log likelihood-356.9171 F-statistic5.459975 Durbin-Watson stat2.379774 Prob(F-statistic) 0.006769
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32 Wald Test: Equation: Untitled Null Hypothesis:C(2)=C(3) F-statistic138.2678Probability0.000000 Chi-square138.2678Probability0.000000
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33 ANOVA By Difference w Regression with interaction terms, USS = 501,136.7 w Regression dropping interaction terms< USS = 502746.3 w Difference is 1,609.6 and is the sum of squares explained by interaction terms w F-test of the interaction terms: F 2, 54 = [1609.6/2]/[501,136.7/54]
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