Journal on Policy & Complex Systems Vol. 2, Issue 2, Fall 2015 | Page 40

Results
Assessing Values-based Sourcing Strategies in Regional Food Supply Networks : An Agent-based Approach

All quantitative metrics were analyzed with analysis of variance ( ANOVA )

tests . The results are reported as significant for a significance level alpha
< 0.05 . Post-hoc Tukey ’ s test with adjusted p-values was used to test for a significant difference in the means for pairwise comparison , for which no a priori hypotheses had been developed . Additionally , Cohen ’ s d was calculated to check the effect size to provide a standard measure to express the differences in means between two groups in standard deviation units . The Cohen ’ s d results are reported as small effects for 0.20 < d < 0.50 , medium effects for 0.50 < d < 0.80 , and large effects for d > 0.80 . Pairwise differences in means will only be discussed if the effect size was greater than 0.20 .
Volume of Food Units Traded
illustrates the means and standard deviations of the volume of food units traded . The volume of food units traded was significant ( F ( 4,4995 ) = 10.17 , p < 0.001 ) across the five different policies . In the figure , means that do not share a letter are significantly different , as calculated by post-hoc analysis . There was a small ( d = 0.24 ) difference between Policy 1 ( No Management ) and Policy 2 ( Supply & Demand ). There was also a small ( d = −0.22 ) difference between Policy 2 and Policy 5 ( Size & Price ).
Figure 1 . The volume of food traded under each policy option . The bars represent standard deviation . Means that do not share a letter are significantly different .
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