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Weak Identification in Peer Effects Estimation

William W. Wang, Ali Jadbabaie

arXiv 6 Aug 2025 · Mathematics — Statistics Theory

arXiv:2508.04897 · PDF · Extracted main text

Abstract

It is commonly accepted that some phenomena are social: for example, individuals' smoking habits often correlate with those of their peers. Such correlations can have a variety of explanations, such as direct contagion or shared socioeconomic circumstances. The network linear-in-means model is a workhorse statistical model which incorporates these peer effects by including average neighborhood characteristics as regressors. Although the model's parameters are identifiable under mild structural conditions on the network, it remains unclear whether identification ensures reliable estimation in the "infill" asymptotic setting, where a single network grows in size. We show that when covariates are i.i.d. and the average network degree of nodes increases with the population size, standard estimators suffer from bias or slow convergence rates due to asymptotic collinearity induced by network averaging. As an alternative, we demonstrate that linear-in-sums models, which are based on aggregate rather than average neighborhood characteristics, do not exhibit such issues as long as the network degrees have some nontrivial variation, a condition satisfied by most network models.

Citation extraction

46
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81
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appendix boundary found by appendix_titled_section at “Appendix” · 67% of the source is main text. Read the extracted text to check this.

Most heavily cited references

The works this paper leans on most, across its whole bibliography — not restricted to papers in our corpus. Ranked by composite intensity, which combines how often a work is mentioned, how many sections mention it, and how much of that falls in the main text rather than the appendix.

ReferenceIntensityMentionsSectionsMain text
1Y. Bramoullé, H. Djebbari, and B. Fortin (2009) Identification of peer effects through social networks1.00085100%
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3L.-F. Lee (2002) Consistency and efficiency of least squares estimation for mixed regressive, spatial autoregressive models0.8947571%
4J. Cai, A. D. Janvry, and E. Sadoulet (2015) Social networks and the decision to insure0.84333100%
5A. Hayes and K. Levin (2024) Peer effects in the linear-in-means model may be inestimable even when identified0.84333100%
6M. Avella-Medina, F. Parise, M. T. Schaub, and S. Segarra (2018) Centrality measures for graphons: Accounting for uncertainty in networks0.64441100%
7D. Acemoglu, V. M. Carvalho, A. Ozdaglar, and A. Tahbaz-Salehi (2012) The network origins of aggregate fluctuations0.64422100%
8L. Anselin (2022) Spatial econometrics0.64422100%
9A. Banerjee, A. G. Chandrasekhar, E. Duflo, and M. O. Jackson (2013) The diffusion of microfinance0.64422100%
10A. Frieze and M. Karoński (2015) Introduction to random graphs0.64422100%

Showing the top 10 of 46 scored citations.

Cited by, within the corpus

arXiv econ.EM papers that cite this one, ranked by how heavily they lean on it.

Citing paperIntensityMentionsSections
1Empirical Challenges with Peers-of-Peers Instruments in the Linear-In-Means Model0.87492
2Peer effect analysis with latent processes0.40511