Replicability, Reproducibility, and Robustness in Political and Social Science Research with Large Language Models
Organizations: Assistant Professor, Department of Political Science, Purdue University. · Assistant Professor, Department of Political Science, University of Western Ontario.
Abstract
This chapter addresses the central reproducibility problem of research with large language models. LLM output is probabilistic and varies across models and versions, which can have significant effects on downstream statistical results. The chapter distinguishes between replicability, reproducibility, and robustness, and proposes a probabilistic standard based on the distribution of results, not identical outputs. It introduces a standardized prompt script, tests within-model variation for encoders and decoders, and develops error-structure analysis to diagnose where models err and whether their errors align. Using three datasets, the chapter shows that measurement choice can reverse the sign of downstream regression coefficients. Existing design-based corrections with gold-labeled subsamples restore validity, but come at the cost of estimate precision. The main contribution of the chapter is a stacked ensemble of open-weight models that improves precision in the correction step while retaining estimate validity.
Figures & tables
| Disclosure item | Information to report |
|---|---|
| Model identification | Name, version, and repository identifier of the LLM or language model used, including whether it is a base, fine-tuned, or otherwise modified model. |
| Model modifications | Any modifications applied to the model, including additional pre-training, fine-tuning, instruction tuning, adapters, prompting frameworks, or other architectural or procedural changes. |
| Prompt(s) | Full text of the final prompt, including system message, category definitions, few-shot examples, and required output format; the number of repeated runs; and a summary of prompt variants tested. |
| Training or fine-tuning data | Description of any additional data used to further pre-train, fine-tune, or adapt the model, including data source, size, selection criteria, preprocessing, and relevant exclusions. |
| Hyperparameters | Relevant training, fine-tuning, or inference hyperparameters, such as learning rate, batch size, number of epochs, optimizer, temperature, top- , maximum tokens, and random seeds where applicable. |
| Computational equipment | Hardware used for training, fine-tuning, or inference, including GPU or CPU type, number of devices, memory, and other relevant computational specifications. |
Scientific Reproducibility
Scientific reproducibility studies whether research methods, data, and software can be inspected and rerun to support published findings.
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