Updated data section to improve explanations and fixed estimation results after incorporating reviewers' comments. Main changes include
- updated data section in particular summary of experimental data and missing data pattern.
- updating the sampling section by adding a figure comparing degree distributions of full and control case samples.
- updating the exponential random graph terms section.
- updating the empirical results section with more detailed descriptions
- adding complete cases analysis in Appendix A and imputation method in Appendix B.
- adding imputation method in Appendix B.
- updating summary statistics in Appendix F.
- updating model results in Appendix G and diagnostics in Appendix H.