Reliable but Design-Sensitive: Instrument Uncertainty in LLM Annotation
Authors: Thomas Reiter, Christoph Kern, Fedor Miasnikov, Sofiia Nikolenko, Rob Chew, Stephanie Eckman, Frauke Kreuter
Organizations: Amazon · Ludwig Maximilian University of Munich, Germany · RTI International, North Carolina, USA · University of Maryland, Social Data Science Center, USA
Large language models (LLMs) can give reliable labels under one setup yet change those labels when researchers make other reasonable design choices. We tested seven LLMs, 12 task designs, three independent runs, and 3,000 tweets labeled for offensive language and hate speech. Repeating the same model and task design produced high agreement (median Fleiss' κ=0.91). Agreement fell when we changed the task design for the same tweets (median Cohen's κ=0.76). Task design and model choice increased the variance of estimated prevalence by factors of 76.7 for offensive language and 110.6 for hate speech compared with sampling variance alone. Variation across LLM task designs reached 560-572 basis points, compared with 270-331 basis points across five human instrument versions. Confidence scores did not solve this problem. They tracked repeated model outputs more closely than agreement with human labels, and grouping six tweets in one prompt lowered mean offensive-language confidence by 660 basis points. We call the variation caused by task design and model choice instrument uncertainty. Researchers can measure it only by comparing reasonable task designs. Repeating one setup or relying on confidence scores cannot replace that test.
Figures & tables
Criterion
Comparison
Validity
Outputs vs. intended construct
Performance
Model vs. human benchmark
Reliability
Same model-design, repeated runs
Sensitivity
Across task designs and models
Table 1: The four evaluation criteria adapted from AAPOR Task Force on Responsible AI Integration in Survey Research (2026) and the comparison required for each.
Offensive language
Hate speech
Variance source added
Component SD
SD cum
± 95%
deff
Component SD
SD cum
± 95%
deff
Sampling only (nominal)
75
75
± 150
1.00
86
86
± 170
1.00
Run-to-run variation
36
83
± 160
1.23
38
94
± 180
1.19
Task design, incl. Model × Design
560
567
± 1,110
57.7
572
579
± 1,140
45.5
Model choice
325
653
± 1,280
76.7
693
903
± 1,770
110.6
Table 2: Cumulative uncertainty in estimated label prevalence. Component standard deviations are estimated from crossed random-effects models of run-level prevalence. Task-design variation combines the task-design and Model × Design variance components. Cumulative standard deviations add independently estimated components as variances. The 95% column reports 1.96×SDcum , and deff is cumulative variance divided by nominal binomial sampling variance. Standard deviations and interval half-widths are reported in basis points.
Figure 3: Stated confidence tracks repeated model outputs more closely than external agreement and changes with presentation format. (a) Observed agreement against stated confidence for another run, another task design, and an individual human annotator. The diagonal marks perfect calibration. (b) Mean stated confidence under individual and batched presentation. All seven models report lower confidence when the same tweets are presented six per call, showing that confidence depends on the instrument used to elicit it.
Appendix figures & tables6 assets
Supplementary material from the paper’s appendix.
Appendix
Term
OL Task
OL Models
OL Random Slopes
HS Task
HS Models
HS Random Slopes
(Intercept)
0.794***
0.765***
0.722***
0.322***
0.389***
0.434***
Task Design Effects
Joint: OL first (vs. Separate)
0.027***
0.027***
0.027
0.023***
0.023***
0.023
Joint: HS first (vs. Separate)
0.011***
0.011***
0.011
− 0.007***
− 0.007***
− 0.007
With Confidence (vs. Without)
0.023***
0.023***
0.023*
− 0.010***
− 0.010***
− 0.010
Batch Prompt (vs. Individual)
− 0.059***
− 0.059***
− 0.059
0.018***
0.018***
0.018
Appendix
Table 3: Pooled mixed-effects LPMs for OL and HS across three nested specifications. Task estimates task-design effects pooled across models; Models adds model identity; Random Slopes allows task-design effects to vary by model.
Term
OL Task
OL Models
OL Task Int.
OL Design Int.
HS Task
HS Models
HS Task Int.
HS Design Int.
(Intercept)
2.608***
2.234***
2.147***
1.998***
− 1.786***
− 1.116***
− 1.169***
− 1.004***
Task Design Effects
Joint: OL first (vs. Separate)
0.401***
0.417***
0.711***
0.432***
0.235***
0.257***
0.259***
0.265***
Joint: HS first (vs. Separate)
0.156***
0.162***
0.162***
0.167***
− 0.075***
− 0.083***
0.073***
− 0.085***
With Confidence (vs. Without)
0.338***
0.351***
0.352***
0.645***
− 0.105***
− 0.115***
− 0.115***
0.220***
Batch Prompt (vs. Individual)
− 0.882***
− 0.917***
− 0.919***
− 0.675***
0.192***
0.210***
0.211***
− 0.366***
Appendix
Table 4: Pooled mixed-effects logistic regressions for OL and HS across four nested specifications: Task, Models, Task Interaction, and Design Interaction.
Term
GPT-4o-mini
GPT-5.4
Mistral Large 3
Mistral Medium 3.5
Llama 3.1 8B
Llama 3.1 70B
Llama 4
SD
Offensive Language
Intercept (Separate, individual, no confidence)
.721
.751
.831
.791
.830
.802
.831
.043
Joint: OL first (vs. Separate)
.068
.002
.032
.003
.064
− .001
.020
.029
Joint: HS first (vs. Separate)
.050
− .022
.027
− .005
.016
.002
.006
.023
With Confidence (vs. Without)
.043
.020
.046
.010
− .003
.028
.014
.018
Batch Prompt (vs. Individual)
− .045
− .001
− .055
.003
− .200
− .053
− .059
.067
Appendix
Table 5: Model-specific mixed-effects linear probability model estimates for offensive language and hate speech. Each model column reports a separate model with a random intercept for tweet. The intercept is the labeling probability under separate calls, individual presentation, and no confidence elicitation. The remaining coefficients are changes relative to that condition.
Model
Within a design
Across designs
Against humans
(Fleiss’ κ )
(Cohen’s κ )
(Cohen’s κ )
GPT-4o-mini
.84–.97 (.94)
.57–.94 (.79)
.41–.62 (.54)
GPT-5.4
.91–.96 (.93)
.69–.92 (.84)
.50–.66 (.59)
Mistral Large 3
.89–.95 (.92)
.46–.90 (.68)
.22–.60 (.47)
Mistral Medium 3.5
.81–.92 (.87)
.61–.91 (.77)
.36–.67 (.56)
Llama 3.1 8B
.19–.80 (.46)
− .00–.81 (.35)
.14–.54 (.34)
Appendix
Table 6: Agreement by model. Min–max (mean) over task designs or design pairs. Within a design is Fleiss’ κ over three runs; across designs is Cohen’s κ between modal labels from two designs of the same model; against humans is Cohen’s κ against the human majority label. The pooled rows give min–max (median).
ECE against agreement with…
Outcome
Another run
Another design
Individual human
Human majority
Offensive language
0.074
0.050
0.218
0.160
Hate speech
0.096
0.059
0.163
0.111
Appendix
Table 7: Calibration and change detection. Panel A reports Expected Calibration Error (ECE) pooled across all seven models for the four agreement targets discussed in Section 4.4 . Panel B reports model-specific ECE for the first three targets, mean stated confidence, the share of items whose modal label changes across designs, and the AUC of confidence as a detector of those changes.
API
Tokens per call
Cost ($), 3 runs
Condition
Calls/run
Task
Tweet
Out
4o-mini
5.4
Indiv., no conf.
3000
517
19
2
0.73
12.33
Indiv., w/ conf.
3000
580
19
4
0.83
14.02
Batch, no conf.
500
639
112
12
0.18
3.09
Batch, w/ conf.
500
724
112
24
0.21
3.67
Appendix
Table 8: Annotation costs for three runs of 3,000 tweets. Batch presentation reduces API calls sixfold and cost by approximately 76% within each model; GPT-5.4 costs approximately 17 times more than GPT-4o-mini.