Table 1.
Simulation results: (i) MPICF: mean percentage improvement in the criterion function realized from using TMKLMedH instead of RH; (ii) MPbetter: Mean percentage of test problems for which TMKLMedH provided a better criterion function value than RH; (iii) MRR: mean ratio of the number of restarts for TMKLMedH to the number for RH within the three-minute time limit; and (iv) ARI recovery measures for row and column clusters for RH and TMLKMedH.
| Design feature levels | MPICF | MPbetter | MRR | RH (Row-ARI) | TMKLMedH (Row-ARI) | RH (Col-ARI) | TMKLMedH (Col-ARI) |
|---|---|---|---|---|---|---|---|
| Overall average | .344 | 47.786 | 24.824 | .745 | .831 | .741 | .829 |
| n = 180 row objects | .264 | 48.698 | 20.543 | .748 | .810 | .715 | .778 |
| n = 540 row objects | .425 | 46.875 | 29.105 | .741 | .852 | .767 | .880 |
| m = 180 column objects | .300 | 50.521 | 18.512 | .710 | .779 | .736 | .807 |
| m = 540 column objects | .388 | 45.052 | 31.136 | .780 | .853 | .746 | .850 |
| K = 3 row clusters | .039 | 29.167 | 23.709 | .967 | .966 | .695 | .791 |
| K = 6 row clusters | .649 | 66.406 | 25.938 | .523 | .696 | .787 | .866 |
| L = 3 column clusters | .038 | 29.948 | 21.900 | .698 | .790 | .968 | .968 |
| L = 6 column clusters | .651 | 65.625 | 27.747 | .792 | .872 | .514 | .690 |
| Even row cluster density | .280 | 41.146 | 27.886 | .785 | .817 | .765 | .849 |
| 60% row cluster density | .409 | 54.427 | 21.762 | .705 | .845 | .717 | .808 |
| Even column cluster density | .240 | 41.667 | 28.412 | .771 | .853 | .788 | .820 |
| 60% column cluster density | .449 | 53.906 | 21.236 | .719 | .809 | .694 | .837 |
| 33% Image matrix density | .367 | 48.438 | 26.753 | .745 | .829 | .740 | .830 |
| 66% Image matrix density | .321 | 47.135 | 22.895 | .744 | .833 | .742 | .827 |
| 70% block strength | .364 | 26.042 | 24.647 | .808 | .911 | .804 | .911 |
| 60% block strength | .325 | 69.531 | 25.001 | .682 | .751 | .678 | .747 |
Table 2.
Comparison of criterion function values for the UNGA networks.
| UNGA Military resolutions network | UNGA Ideological resolutions network | ||||||||
| K | L | TMKLMedK | RH | TS | VNS | TMKLMedH | RH | TS | VNS |
| 4 | 4 | 1743 | 1743 | 1743 | 1743 | 4220 | 4220 | 4220 | 4220 |
| 4 | 5 | 1730 | 1730 | 1730 | 1730 | 4144 | 4144 | 4144 | 4144 |
| 4 | 6 | 1730 | 1730 | 1730 | 1730 | 4136 | 4136 | 4144 | 4136 |
| 4 | 7 | 1730 | 1730 | 1730 | 1730 | 4131 | 4136 | 4136 | 4136 |
| 5 | 4 | 1713 | 1713 | 1713 | 1713 | 4200 | 4200 | 4200 | 4200 |
| 5 | 5 | 1663 | 1663 | 1663 | 1663 | 4020 | 4020 | 4020 | 4020 |
| 5 | 6 | 1649 | 1657 | 1649 | 1649 | 3947 | 3950 | 3947 | 3947 |
| 5 | 7 | 1646 | 1650 | 1646 | 1649 | 3890 | 3896 | 3947 | 3890 |
| 6 | 4 | 1707 | 1707 | 1709 | 1709 | 4194 | 4198 | 4194 | 4196 |
| 6 | 5 | 1633 | 1633 | 1633 | 1633 | 4001 | 4001 | 4001 | 4001 |
| 6 | 6 | 1614 | 1619 | 1612 | 1612 | 3841 | 3841 | 3841 | 3841 |
| 6 | 7 | 1599 | 1613 | 1608 | 1599 | 3763 | 3772 | 3763 | 3763 |
| 7 | 4 | 1702 | 1707 | 1707 | 1707 | 4194 | 4194 | 4194 | 4196 |
| 7 | 5 | 1627 | 1634 | 1627 | 1630 | 3997 | 4001 | 3999 | 3998 |
| 7 | 6 | 1577 | 1588 | 1577 | 1577 | 3822 | 3822 | 3825 | 3822 |
| 7 | 7 | 1565 | 1566 | 1565 | 1565 | 3691 | 3695 | 3691 | 3691 |
1 Note: The criterion function values for the RH, TS, and VNS methods were taken from the article by Brusco et al. (2013a, Tables 2 and 3, pp. 204-205). The cell values shown in bold font reflect instances where the heuristic method failed to match the best criterion function value found across all four methods
Table 3.
Comparison of criterion function values and number of restarts for the MovieLens network.
| Criterion function values | Number of restarts | ||||||
| K | L | TMKLMedH | RH | PICF | TMKLMedH | RH | RatioTMKLMedH / RH |
| 2 | 2 | 90971 | 90971 | 0.000 | 2000 | 342 | 5.848 |
| 2 | 3 | 90889 | 90901 | 0.013 | 1980 | 201 | 9.851 |
| 2 | 4 | 90875 | 90900 | 0.028 | 1863 | 171 | 10.895 |
| 2 | 5 | 90875 | 90899 | 0.026 | 1799 | 129 | 13.946 |
| 2 | 6 | 90875 | 90892 | 0.019 | 1749 | 113 | 15.478 |
| 2 | 7 | 90875 | 90889 | 0.015 | 1687 | 103 | 16.379 |
| 3 | 2 | 90971 | 90971 | 0.000 | 1494 | 129 | 11.581 |
| 3 | 3 | 88846 | 88859 | 0.015 | 1345 | 86 | 15.640 |
| 3 | 4 | 88799 | 88858 | 0.066 | 1176 | 80 | 14.700 |
| 3 | 5 | 88783 | 88864 | 0.091 | 1130 | 59 | 19.153 |
| 3 | 6 | 88781 | 88852 | 0.080 | 1109 | 56 | 19.804 |
| 3 | 7 | 88773 | 88823 | 0.056 | 1111 | 52 | 21.365 |
| 4 | 2 | 90971 | 90971 | 0.000 | 1218 | 86 | 14.163 |
| 4 | 3 | 88846 | 88864 | 0.020 | 1079 | 57 | 18.930 |
| 4 | 4 | 87603 | 87907 | 0.347 | 936 | 42 | 22.286 |
| 4 | 5 | 87205 | 87237 | 0.037 | 893 | 42 | 21.262 |
| 4 | 6 | 87142 | 87550 | 0.468 | 806 | 36 | 22.389 |
| 4 | 7 | 87124 | 87748 | 0.716 | 782 | 36 | 21.722 |
| 5 | 2 | 90971 | 90971 | 0.000 | 1041 | 68 | 15.309 |
| 5 | 3 | 88850 | 88863 | 0.015 | 897 | 42 | 21.357 |
| 5 | 4 | 87165 | 87662 | 0.570 | 779 | 34 | 22.912 |
| 5 | 5 | 86498 | 87146 | 0.749 | 747 | 33 | 22.636 |
| 5 | 6 | 86043 | 86514 | 0.547 | 680 | 28 | 24.286 |
| 5 | 7 | 86010 | 86082 | 0.084 | 647 | 24 | 26.958 |
| 6 | 2 | 90971 | 90971 | 0.000 | 897 | 56 | 16.018 |
| 6 | 3 | 88846 | 88876 | 0.034 | 784 | 32 | 24.500 |
| 6 | 4 | 87172 | 87720 | 0.629 | 673 | 29 | 23.207 |
| 6 | 5 | 86105 | 87338 | 1.432 | 651 | 24 | 27.125 |
| 6 | 6 | 85790 | 86678 | 1.035 | 597 | 21 | 28.429 |
| 6 | 7 | 85529 | 86197 | 0.781 | 567 | 18 | 31.500 |
| 7 | 2 | 90971 | 90971 | 0.000 | 792 | 46 | 17.217 |
| 7 | 3 | 88846 | 88883 | 0.042 | 690 | 30 | 23.000 |
| 7 | 4 | 87169 | 87456 | 0.329 | 603 | 22 | 27.409 |
| 7 | 5 | 85999 | 86330 | 0.385 | 572 | 20 | 28.600 |
| 7 | 6 | 85573 | 85982 | 0.478 | 511 | 15 | 34.067 |
| 7 | 7 | 85188 | 85617 | 0.504 | 498 | 14 | 35.571 |

Figure 1.
Heatmaps for RH (top panel) and TMKLMedH (bottom panel) criterion values for the MovieLens network.

Figure 2.
RH (top panel) and TMKLMedH (bottom panel) image matrices for blockmodels obtained using K = L = 5. The sizes of each cluster of individuals (n 1,…, n 5) and movies (m 1,…, m 5) are also provided.