Table 2 Validation.

Validation results of the systems thinking network are displayed for each of the following trim levels: three, five, seven, and nine or more co-citations. The number of documents and the number of co-citations in each network are indicated. Internal consistency is reported as Spearman’s rank correlations of times cited by source documents to degree of co-citation. Community validity was tested using a χ2 test for independence between assigned network communities and subject communities. Stability was measured as the number of co-cited documents in the comprehensive network also found in the systems thinking network, and a Spearman’s rank correlation of the degree of co-citation for documents matched between the two networks.

Systems thinking network
trim levels
≥3≥5≥7≥9
Network metrics
Co-cited documents (number of nodes)246713519
Co-citations (number of edges)1,29227110544
Internal consistency
Spearman’s value (S)1,099,36915,4682151584
P value<0.001<0.001<0.0010.034
ρ0.560.740.700.49
Community validity
X2494.5585.4045.1617.47
Degrees of freedom (df)280483012
P value<0.001<0.0010.0370.13
Stability to comprehensive network
Number of matching documents68362418
S26,6134,4591716510
P value<0.0010.00950.250.47
ρ0.450.420.250.47