Why we need a rubric
When evaluating data annotation services, the comparison points are often velocity and price. To compete on those terms, some vendors take shortcuts that diminish the value of the data, or achieve lower prices through unethical treatment of the human beings doing the actual annotation. Discussions of the vendor’s processes and their adherence to best practices sometimes appear on their websites or in conversation, but it can be difficult to objectively compare providers. Having a widely used rubric shared by the data community can formalize these definitions, remind us of the hidden layers in data sourcing, enable apples-to-apples comparison, and reduce surprises when the dataset is delivered.
Furthermore, when a project team has selected a vendor who isn’t the lowest bid, they often need to justify their choice to a procurement team. A scorecard that objectively measures each vendor against a set of standard crieria should make it easier to explain why spending additional money is appropriate, in pursuit of essential high-quality data.
Vendors will also benefit from such a rubric, which can help them more effectively explain to new clients the value that they provide. It will reduce the pressure to compete solely on time and money, allowing a richer ecosystem to thrive with different providers offering different tradeoffs among price, schedule, and quality.
Interpreting the rubric
Each category presents a summary of practices we have encountered with various vendors, assigned to four levels. (An empty level in a category means we have not yet encountered a practice that we would assign to that level.)
- Excellent: This is a best practice and exceeds expectations.
- Good: This is adequate for most cases and is the usual expectation.
- Poor: Below expectations; a warning sign that the provider may deliver poor-quality data.
- Unacceptable: A major deficiency; even one of these usually disqualifies a provider.
This rubric, while shared, is not to be mindlessly applied across all projects. Your team might adjust the “grade” for some items to emphasize what you consider important. We welcome your feedback on what should be added or judged differently; please send email to agreene@adobe.com.
Those interested in a detailed explanation of many of these topics will find Monarch (2021) useful.
The Rubric
| Taxonomy/Ontology/Annotation Guide: Versioning | |
| Excellent | Uses semantic versioning for the instructions. (See semvar.org) |
| Good | Uses timestamp or other linear version number for the instructions. Maintains a change log. |
| Poor | Lacks a formal process for tracking changes and ensuring client agreement on changes to the taxonomy/ontology/instructions. |
| Unacceptable | Makes unilateral changes; makes it difficult to keep client and provider versions “in sync”. |
| Taxonomy/Ontology/Annotation Guide: Language | |
| Excellent | Manually translates instructions into the annotators’ native language, when appropriate. The client is given the opportuty to review the translation. |
| Good | When annotators are not fluent in the language in which the client has written guidelines, ensures that the instructions are easy to understand, with client collaboration and approval. |
| Poor | Does not review instructions for readability by non-fluent speakers of the language in which the guidelines are written, even when that is needed. |
| Unacceptable | Relies on machine translation of instructions without manual verification. |
| Taxonomy/Ontology/Annotation Guide: Questions | |
| Excellent | Has a UI in the annotation tool for annotator questions and client responses. Considers annotator feedback important and includes that time in their pay. |
| Good | Can collect annotators’ questions in the UI, but responses delivered externally. Provides client with opportunity to test-drive the annotators’ experience. |
| Poor | Uses an out-of-context system (e.g., a shared spreasheet) for annotator queries. |
| Unacceptable | Lacks any way for annotators to ask questions. |
| Taxonomy/Ontology/Annotation Guide: Testing and Refinement | |
| Excellent | Has experts in annotation techniques and HCI review the guidelines and suggest improvements to increase accuracy and reduce cognitive load. Coaches underperforming annotators; firing them only as a last resort. |
| Good | Tests the instructions for clarity and completeness with small group of annotators before scaling up. Annotators have option to respond “can’t answer”. Provides annotators sufficient time to understand the task. Distinguishes between training material and the taxonomy. |
| Poor | Insists that guidelines must cover every eventuality, even though that adds cognitive costs while coverage only asymptotically approaches being complete. |
| Unacceptable | Rushes to scale up annotation without first collecting data that confirms that the guidelines are clear and are being consistently applied. |
| Ethical treatment of annotators: Payment | |
| Excellent | Full-time, paid salary, with benefits. |
| Good | Part-time, paid hourly, including time spent in training and on breaks. |
| Poor | Paid per annotation, works out to a living wage in the annotator’s location. |
| Unacceptable | Paid per annotation, works out to below living wage in the annotator’s location. |
| Ethical treatment of annotators: Work conditions | |
| Excellent | Annotation interface is accessible. Coaches underperforming annotators, firing them only as a last resort. |
| Good | Provides annotators with appropriate equipment (e.g., large monitors). Provides breaks and variety to avoid fatigue. |
| Poor | Neglects ergonomic needs of annotators. Sets unrealistic quotas. |
| Unacceptable | Lacks appropriate pandemic safety precautions. |
| Assessing annotation quality | |
| Excellent | Provider’s quality team manually reviews a random sample of data frequently. Provides dashboard (updated daily) for client to monitor detailed metrics. In multi-stage workflows, annotators can flag bad results from previous stages. Builds models to predict annotation errors based on metadata. Reports accuracy estimates for each task with confidence/credibility intervals. |
| Good | Identifies high-risk items for additional manual review. Sets and meets higher quality goals for test data. Provides UI for “acceptance testing” by client on a rapid cadence. Reports accuracy estimates for each task using a statistically valid approach. |
| Poor | Uses only simplistic inter-annotator agreement to monitor dataset consistency. Fails to revisit earliest annotations once annotators have gained experience. |
| Unacceptable | Flawed data is discarded (which can introduce bias) instead of being corrected. Task-level accuracy not reported or lacks an explanation of how it is computed. |
| Assessing annotator reliability | |
| Excellent | Uses statistical tests to identify outlier annotators for each question. |
| Good | Regularly adds items whose correct answer is known, to monitor annotator quality throughout the project. Uses statistical tests to monitor/identify questions with high disagreement. Uses statistical tests and tracking of IP addresses to identify bots or collusion between supposedly independent annotators. |
| Poor | Uses simplistic IAA to identify outlier annotators. Rejects minority opinions out of hand (instead of trying to understand the cause for the disagreement). |
| Unacceptable | Lacks IAA or statistical monitoring. Fails to exclude or review data previously obtained from annotators who turn out to be unreliable. |
| Merging/adjudication of individual annotations | |
| Excellent | Merging strategy accounts for individual annotators’ previous accuracy. (E.g., reweighting of individuals or modeling correlations among annotators.) Annotators can review/revisit their work before it is finalized. |
| Good | Client can specify merging strategy (e.g., median, or priority voting, etc.) Number of annotators per task clearly specified and statistically justified. |
| Poor | Decisions depend only on majority vote of annotators. |
| Unacceptable | Some decisions are a single annotator’s opinion. (Note: When annotator has demontrated high reliability or is a designated SME, this may be defensible.) |
| Data Delivery | |
| Excellent | Provides detailed raw data including annotator ID, date+time of annotation, elapsed time for annotation, annotator’s location and/or locale (for modeling sources of error such as unanticipated cultural bias or a poor translation of the instructions), previous versions for this item from this annotator, version number of the instructions under which each datum was collected and annotated (plus merged annotation data). |
| Good | Provides merged data and individual responses but with incomplete metadata. |
| Poor | Provides merged data plus individual responses but with minimal metadata. |
| Unacceptable | Provides merged data only. Does not exclude or revisit previously gathered data from annotators who turn out to be unreliable. |
| Acquiring Unlabeled Data: Ethics | |
| Excellent | Obtains informed consent from data providers. Offers compensation to content creators when appropriate. |
| Good | Relies on sources in the public domain and CC-style licenses. |
| Poor | Scrapes the web for publicly visible data, relying on Fair Use carve-outs in copyright law in the relevant geographies. |
| Unacceptable | Violates copyright law in the relevant geographies. Does not comply with privacy laws such as GDPR. |
| Acquiring Unlabeled Data: Bias and Domain Shift | |
| Excellent | Uses ML approaches such as clustering to monitor distribution for societal bias and domain mismatch, and resamples as needed. |
| Good | Uses heuristics to monitor distribution for societal bias and domain mismatch, and resamples as needed. |
| Poor | Only monitors for domain shift. |
| Unacceptable | Does not monitor for bias or domain shift. |
| Selection Function/Prioritizing Items | |
| Excellent | Provides methods for (a) distribution sampling using provider’s embeddings, and (b) uncertainty sampling using provider’s off-the-shelf model. |
| Good | Provides API to allow client to prioritize data (distribution, uncertainty based on model under development). Provides control over ratio of sampling methods (random, distribution, uncertainty) and allows for that to be updated over time. |
| Poor | Does not empower client to control prioritization or selection within the queue. |
| Unacceptable | Uses filenames or database IDs to control the order of annotation (because these may encode metadata, such as when items are in chronological order, and this may prime or bias the annotators). |
| Starting with Seeded Data | |
| Excellent | Compares seeded and unseeded (control-group) annotation tasks to measure impact of anchoring bias. Can seed data via in-house computational approaches if client desires. |
| Good | Can seed annotations using data provided by client. |
| Poor | - |
| Unacceptable | Automates annotation or seeds data via heuristics, models, or algorithms without client’s knowledge and assent. |
Rubric version: 0.3.2, last saved 2021-09-30 19:53