Automatic Coding of Text Answers to Open-Ended Questions: Should You Double Code the Training Data?
Bibliographic record
Abstract
Open-ended questions in surveys are often manually coded into one of several classes (or categories). When the data are too large to manually code all texts, a statistical (or machine) learning model must be trained on a manually coded subset of texts. Uncoded texts are then coded automatically using the trained model. The quality of automatic coding depends on the trained statistical model, and the model relies on manually coded data on which it is trained. While survey scientists are acutely aware that the manual coding is not always accurate, it is not clear how double coding affects the classification errors of the statistical learning model. We investigate several budget allocation strategies when there is a limited budget for manual classification: single coding versus various options for double coding where the number of training texts is reduced to maintain the fixed budget. Under fixed budget, double coding improved prediction of the learning algorithm when the coding error is greater than about 20–35%, depending on the data. Among double-coding strategies, paying for an expert to resolve differences performed best. When no expert is available, removing differences from the training data outperformed other double-coding strategies. When there is no budget constraint and the texts have already been double coded, all double-coding strategies generally outperformed single coding. As under fixed budget, having an expert to solve disagreement in training texts improves accuracy most, followed by removing differences.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.143 | 0.438 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.005 | 0.005 |
| Science and technology studies | 0.002 | 0.003 |
| Scholarly communication | 0.003 | 0.005 |
| Open science | 0.003 | 0.005 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.008 | 0.004 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".