A previous report (Kusakabe, 2011, in Japanese) warned about an interpretation of a scatter diagram with coordinates expressed in the percentages or per capita data. Since most of the social indicators obey the Law of Power Function (Kusakabe, 2011), the scatter diagram of such indicaters in terms of ratio (percentage or per capita) inevitably shows positive or negative spurious correlations in cross section data analysis, irrespective of the causation. These spurious correlations are induced by the population size effect. Here, I will critically examine Putnam's Social Capital Index (SCI) in “Bowling Alone, Part 4." Putnam's SCI is highly correlated with the population size (Fig.12; R=-0.487**). Path analysis shows clear effect of population size on Putnam's SCI (Fig. 15(2)). Thus, Putnam's SCI inevitably induces both spurious correlations with most of the various social indicators and strong bias in his estimates for Social Capital Index. However, if we exclude the population size effect from Putnam's SCI using a regression method,the resulting regression residuals (adjusted SCI or the Regression-based score, R-score, defined by Kusakabe 2002a,b,c in Japanese) almost coincide with a Regression-based score of the number of nonprofit organizations in the United States (Fig.16(1),(2), R=0.663**).
Both of the Regression-based scores of Putnam's SCI(adjusted SCI) and those of NPOs significantly correlate with the Regression-based scores of murders (Fig.20(1),21(1); R=-0.776**and -0.605**, respectively). Path analyses on both Putnam's adjusted SCI and R-score for NPOs clearly show the strong effect on the R-score for murders (Fig.20(2),21(2); pass coefficient, -0.776** and -0.605**, respectively). These results disclose firm evidences for “cultural embeddedness" of Social Capital in the United States. Thus, Social Capital, indeed, can be measurable with these Regression -based scores for the number of nonprofit organizations or Putnam's adjusted SCI (Regression-based SCI score).
The revised version of Putnam's barometric map of America's Social Capital (Figure 25) is successfully presented in this study in terms of R-score for nonprofit organizations in the United States of America.