Library · Machine learning & AI

What Large Language Models & Prompt Engineering got wrong, from 35 theses

Summary written by a model from the records below: The records demonstrate that prompting and fine-tuning large language models frequently underperform simpler supervised baselines across domain-specific classification, sequence extraction, and code synthesis tasks. Furthermore, manual prompt engineering, complex reasoning frameworks, and rigid prompt constraints often fail to improve output quality and can induce severe reasoning degradation. These records come from graduate theses, 2022 to 2026, each labeled with its degree where the repository states it, and each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.

35
theses
13
institutions
38
failure records
5
failure modes

Plus 10 problems the authors left open, listed at the end.

Failure modes, by theses reporting them

Select a mode to jump to its records.

Prompt-based classification underperforms supervised classifiers and simple baselines on specialized text
8
8 theses · 5 institutions · 10 records
Prompt engineering and complex prompting frameworks fail to improve performance and can overwhelm reasoning
10
10 theses · 6 institutions · 10 records
Prompting for code generation, software repair, and automated evaluation yields generic or invalid outputs
7
7 theses · 4 institutions · 8 records
General-purpose language models fail at specialized entity extraction and relational reasoning
6
6 theses · 5 institutions · 6 records
Mathematical reasoning and trajectory generation degrade under rigid prompting and intermediate step constraints
4
4 theses · 3 institutions · 4 records

Prompt-based classification underperforms supervised classifiers and simple baselines on specialized text

8 theses · 5 institutions

Zero-shot and few-shot prompting fail to capture complex domain rubrics and class imbalances, trailing behind simpler supervised models, dictionary benchmarks, and rule-based baselines. Performance frequently drops to near random chance on subjective, moral, and legal constructs, with accuracy degrading further as candidate author sets expand.

Tried and failed

few-shot prompting of pretrained language models applied to domain-specific text classification. Outcome: worse than baseline. Reason: general pretraining lacks alignment with specialized, nuanced coding rubrics compared to supervised simple classifiers

Evaluating language models applied to student thinking about experiments · Cornell · PhD

Tried and failed

prompting pretrained generative large language models applied to complex domain-specific text classification. Outcome: worse than baseline. Reason: zero-shot and few-shot prompting failed to capture complex domain constructs compared to fine-tuned domain-specific encoders

Modeling Legal Constructs · Cornell · PhD

Tried and failed

prompt-based zero-shot large language model classification applied to student text behavior classification. Outcome: worse than baseline. Reason: produced substantially lower AUC and more than double the false positives compared to embedding-based classifiers

MEASURING AND UNDERSTANDING STUDENTS’ SELF-REGULATED LEARNING IN TEXTUAL DATA IN COMPUTER-BASED LEARNING ENVIRONMENTS · Penn · PhD

Lost to a baseline

Most LLM prompts for stance extraction across all 1,000 tweets had lower overall accuracy than a naive majority-class baseline

Leveraging social media data and large language models for understanding public health behaviours in the context of infectious diseases and vaccination · EPFL · PhD

Considered and rejected

Considered and rejected: Rejected relying solely on in-context prompting (zero-shot, few-shot, and Chain-of-Thought) for specialized legal construct classification due to poor performance and severe class imbalance errors.

Modeling Legal Constructs · Cornell · PhD

Considered and rejected

Considered and rejected: Rejected LLM-based prompting (e.g. GPT-4 Turbo) for input authorship inference because macro-F1 drops sharply as author set scales to 100-200 candidates.

Online identity inference, impersonation and mitigation strategies · Imperial · PhD

Considered and rejected

Considered and rejected: Rejected Large Language Models (LLMs) in favor of LDA topic models and dictionary-based content analysis.

The Rise of Counterpopulism: a Comparative Analysis of Social Movements Resisting Right-Wing Populism in Power in Italy, the United Kingdom and the United States of America · Scuola Normale Superiore · PhD

Tried and failed

large language model zero-shot text classification applied to moral framing text annotation. Outcome: no signal. Reason: LLM predictions failed to align with validated domain-specific dictionary benchmarks across categories

COMPUTATIONAL METHODS ON POLITICAL MORAL LANGUAGE IN ONLINE SPACES · Cornell · PhD

Tried and failed

zero-shot large language model prompting applied to nuanced text annotation tasks. Outcome: no signal. Reason: models achieved near-random performance on subjective constructs

More Than a Sum of Its Parts: Teamwork Through a Multidimensional Lens · Penn · PhD

Lost to a baseline

Zero-shot prompting on several LLMs (including Llama3 8B and Mistral 7B) achieved lower accuracy than the rule-based VADER sentiment analysis baseline

Leveraging social media data and large language models for understanding public health behaviours in the context of infectious diseases and vaccination · EPFL · PhD

Prompt engineering and complex prompting frameworks fail to improve performance and can overwhelm reasoning

10 theses · 6 institutions

Iterative prompt adjustments, human annotation guidelines, and formatting shifts such as code syntax or perspective changes provide negligible performance gains over simple prompts. Additionally, structured prompting schemes like tree structures and chain of thought overwhelm lower-capacity models, causing classification instability and confusion.

Tried and failed

manual iterative prompt engineering applied to large language model text annotation. Outcome: no signal. Reason: manual refinements yielded only marginal performance gains over baseline prompts

Human-Centered AI in Computational Social Science: Evaluating Automated Annotation with Large Language Models · Penn · PhD

Tried and failed

using human annotation guidelines as LLM prompts applied to text classification and rationale extraction. Outcome: worse than baseline. Reason: instructions optimized for human annotators did not translate effectively to LLM reasoning and yielded no improvement

Towards Bridging and Governing Decentralized Communities · MIT · PhD

Tried and failed

First-person perspective text augmentation applied to Clinical text classification. Outcome: no signal. Reason: Perspective shift provided no meaningful performance gain over baseline prompts

Transforming SDOH Screening: Towards a General Framework for Transformer-based Prediction of Social Determinants of Health · Virginia Tech · Master's

Tried and failed

prompt engineering on large language models applied to zero-shot tone classification of transcripts. Reason: re-prompting failed to correct the model's conservative classification bias, causing poor agreement with human annotators

Investigating the Structural Evolution of Ad Design: Computational Analysis of Information Content and Interactivity in Ads · MIT · Master's

Considered and rejected

Considered and rejected: Rejected complex prompt instructions for closed-book QA, sticking to 'Q: <question> A:' because sophisticated prompts did not improve accuracy enough to justify model overfitting risks.

Beyond Scaling: Frontiers of Retrieval-Augmented LMs · University of Washington · PhD

Considered and rejected

Considered and rejected: Rejected relying solely on grade-level prompt engineering to vary summary complexity because lower grade prompts often generated complex language.

Language as Design: Adapting Language to Different Online Audiences · University of Washington · PhD

Tried and failed

tree-structured prompting applied to small language model reasoning. Outcome: worse than baseline. Reason: representational overhead overwhelmed the capacity of smaller models

Backward Reasoning in LLMs: A Strategy for Identifying Irrelevant Context in Mathematical Word Problems · Virginia Tech · Master's

Tried and failed

chain-of-thought prompting with lower-capacity LLM applied to complex multi-class text annotation. Outcome: unstable. Reason: Model exhibited confusion, high labeling variability, and frequent classification errors compared to larger models

Value Expressions in Patents: Their Relationship to Patent Valuation and Technological Orientation · Georgia Tech · PhD

Tried and failed

code-formatted prompting of large language models applied to general natural language processing tasks. Outcome: worse than baseline. Reason: code structure constraints impaired general language and reasoning tasks compared to natural text prompts

Structured Event Reasoning with Large Language Models · Penn · PhD

Considered and rejected

Considered and rejected: Rejected using zero-shot LLM prompts with detailed definitions and implicit instructions, choosing concise prompts without added explanations.

Machine Learning Approaches to Understanding Legislative Economic Discourse · University College Dublin · PhD

Prompting for code generation, software repair, and automated evaluation yields generic or invalid outputs

7 theses · 4 institutions

Models fail at complex algorithmic state transitions, build conflict repairs, and exploit synthesis because they lack vital architectural context and overgeneralize explicit domain rules. In evaluation and code review settings, models generate vague, repetitive feedback and full solutions rather than pinpointing localized errors.

Tried and failed

large language models for code repair applied to software build conflict resolution. Reason: generated meaningless outputs and achieved low resolution accuracy on complex merge conflict tasks

Automating The Detection and Resolution of Build Conflicts in Software Merge for Java Programs · Virginia Tech · Doctorate

Tried and failed

large language models for automated grading applied to student engineering derivations and solutions. Reason: Outputted full solutions and generic suggestions rather than pinpointing specific error locations in student work

Developing an Automated Practice Environment and Feedback Engine for Guided Instruction in the Deformable Bodies Course · Virginia Tech · Doctorate

Tried and failed

prompting LLMs with explicit domain-specific rules applied to automated code conflict resolution. Outcome: worse than baseline. Reason: models overgeneralized explicit rules, incorrectly misapplying patterns to unrelated code contexts

Automating The Detection and Resolution of Build Conflicts in Software Merge for Java Programs · Virginia Tech · Doctorate

Tried and failed

prompting large language models for algorithmic generation applied to complex dynamic programming problems. Outcome: did not generalise. Reason: models fail on complex algorithmic reasoning requiring multi-step state transitions and optimal substructure

Are Bigger LLMs Always Better? A Study of Open and Closed-Source Models in Code Generation and Translation · Virginia Tech · Master's

Tried and failed

prompting large language models for critique generation applied to evaluating complex student writing. Outcome: worse than baseline. Reason: generated critiques were vague, generic, and repetitive compared to human instructor assessments

Addressing teachers’ needs for integrating generative AI into a pedagogical feedback model · Iowa State · Master's

Considered and rejected

Considered and rejected: Rejected using Large Language Models (ChatGPT) for writing critical code because debugging machine-generated logic errors takes more time than writing manually and models cannot answer contextual 'why' questions.

Code, communication, and culture : an ethnography of open source quantum software communities · UT Austin · PhD

Considered and rejected

Considered and rejected: Rejected open-ended optimization prompts (e.g., 'make my code faster') and multi-file refactoring with ChatGPT due to lack of extensive non-code and architectural context

Studying Developers’ Engagement with ChatGPT for Issue Resolution · Saskatchewan · Master's

Tried and failed

zero-shot large language model generation without exemplars applied to generating software vulnerability exploits. Outcome: no signal. Reason: the model lacked domain-specific context and test patterns needed to synthesize functional exploit payloads

Secure Coding Practice in Java: Automatic Detection, Repair, and Vulnerability Demonstration · Virginia Tech · Doctorate

General-purpose language models fail at specialized entity extraction and relational reasoning

6 theses · 5 institutions

Zero-shot prompts fail to identify complex confidential text, temporal knowledge graph relations, biological perturbations, and viral mutations without task-specific fine-tuning or retrieval. Generative language models underperform dedicated encoder architectures like BERT on token-level span classification and clinical information extraction.

Tried and failed

direct zero-shot prompting of large language models applied to clinical note information extraction. Outcome: did not generalise. Reason: failed to adapt and performed poorly on advanced reasoning models without structured reasoning or fine-tuning

Machine Learning Approaches for Drug Combination Discovery · Cornell · PhD

Tried and failed

fine-tuned large language models for sequence extraction applied to named entity recognition. Outcome: worse than baseline. Reason: Generative LLMs underperformed specialized smaller encoder models like BERT on token-level span classification tasks.

Consistency-aware and LLM-assisted methods for named entity recognition · Iowa State · PhD

Tried and failed

zero-shot prompting with basic statutory definitions applied to confidential information redaction in text. Outcome: did not generalise. Reason: Abstract legal definitions lacked sufficient context to identify complex, non-standard sensitive categories accurately.

LLM-Assisted Detecting and Redacting Confidential Information for Government Information Disclosure · Virginia Tech · Master's

Tried and failed

zero-shot large language model reasoning applied to temporal knowledge graph link prediction. Outcome: did not generalise. Reason: models fail to understand structured graph entities and temporal relations without specialized fine-tuning

Temporal link prediction in the wild · Imperial · PhD

Tried and failed

zero-shot prompting of general-purpose LLMs applied to extracting viral mutations from text. Outcome: no signal. Reason: general-purpose models achieved extremely low recall and F1 scores on domain-specific extraction

Discovering Viral Hosts, Mutations, and Diseases using Machine Learning · Virginia Tech · Doctorate

Tried and failed

direct LLM zero-shot prompting without retrieval applied to biological perturbation effect prediction. Outcome: no signal. Reason: models lacked external experimental context and structured reasoning to predict perturbation outcomes above chance

Practical Algorithms for Modeling Causality to Accelerate Scientific Discovery · MIT · PhD

Mathematical reasoning and trajectory generation degrade under rigid prompting and intermediate step constraints

4 theses · 3 institutions

Explicit symbolic equation prompts and intermediate answer generation degrade downstream problem-solving accuracy and answer consistency in multi-step mathematical reasoning. Similarly, empty noise exclusion hints, positive-only fine-tuning paths, and out-of-distribution return targets lead to policy collapse and performance loss.

Tried and failed

prompting language models with explicit symbolic equations applied to synthetic tabular data generation. Outcome: worse than baseline. Reason: LLMs struggle with complex mathematical reasoning, degrading generation accuracy and increasing MSE

New Approaches to Synthetic Tabular Data Generation · Virginia Tech · Doctorate

Tried and failed

prompting with an empty noise exclusion hint applied to mathematical reasoning under noisy input. Outcome: worse than baseline. Reason: providing an empty exclusion hint degraded downstream problem-solving performance compared to explicit noise identification

Quantitative reasoning ability of large language models under noisy data · Iowa State · Master's

Tried and failed

Supervised fine-tuning on positive reasoning paths only applied to Mathematical question answering. Outcome: worse than baseline. Reason: Lacked error-correction and self-revision mechanisms present in prompting

Knowledge-Centric Multimodal Intelligence: Understanding, Reasoning, and Generation · Virginia Tech · Doctorate

Tried and failed

prompting decision transformer with out-of-distribution return targets applied to offline reinforcement learning trajectory generation. Outcome: worse than baseline. Reason: conditioning on overly high target returns far from the dataset average caused policy collapse

THREE ESSAYS ON DISCRETE CHOICE LATENT CLASS MODEL, ONLINE REUSABLE RESOURCE ALLOCATION AND TRANSFORMER MODEL FOR OFFLINE REINFORCEMENT LEARNING · Cornell · PhD

Left open by the authors

Problems the authors named and did not get to.

Left open

Evaluate zero-shot, one-shot, and few-shot prompting on LLM annotation performance for pedagogical discourse moves in classroom transcripts. Blocker: Access to the annotated elementary classroom transcript dataset.

Comparing human and generative AI annotation performance: Understanding linguistic features of teacher talk in classroom discussions · Iowa State · Master's

Left open

Apply the PARSE framework to evaluate LLM perturbation bias on prompts in healthcare, legal guidance, and job matching domains. Blocker: None

PARSE: A Framework for Evaluating Linguistic and Typographical Perturbation Bias in Large Language Models · York University · Master's

Left open

Benchmark general-purpose large language models against specialized predictive models on reaction condition tasks such as solvent prediction. Blocker: None

Integrating AI across the Chemistry Discovery Cycle: Advancing Sustainable Chemistry through Digital Methods · EPFL · PhD

Left open

Compare empirical neural scaling statistics in large language models against predictions from prior analytical scaling models. Blocker: None

Decomposing Deep Neural Network Minds into Parts · MIT · PhD

Left open

Implement and evaluate early-fusion n-gram LM prediction prompting or conditioning for neural LLM text generation. Blocker: None

Navigating the Ocean of Language Model Training Data · University of Washington · PhD

Left open

Adapt summarization evaluation prompting methods to handle documents exceeding context limits and structured tabular inputs. Blocker: None

Fine-grained evaluation for text summarization · UT Austin · PhD

Left open

Apply advanced large language models and hybrid quantum-classical algorithms to source code representations for software defect prediction. Blocker: The unfinished work lacks concrete specifications, specific model architectures, or target benchmarks

Enhancing Software Defect Prediction: Investigating Diverse Representations of Source Code as Feature Values in Classical and Quantum Machine Learning Approaches · Saskatchewan · PhD

Left open

Apply lifelong learning fine-tuning techniques to large language models for generating automated code review comments across evolving codebases. Blocker: None

Towards Sustainable AI for Continuous Integration Quality Gates · Queen's University · PhD

Left open

Apply large language models to resolve grounding and policy errors in compositional decision-making tasks. Blocker: None

Enabling Compositional Generalization of AI Systems · MIT · PhD

Left open

Fine-tune large language models such as Stable Beluga and GPT-4 on organization-specific code review datasets. Blocker: Requires private organization-specific code review datasets.

Enhancing code review for improved code quality with language model-driven approaches · York University · Master's

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