A bag of words gives every type its
own axis. Two filings that never share a string have inner product zero, even when one says “impairment” and the other
says “write-down” in the same local context. An embedding is a dense vector for the word, learned so that words which
keep similar company land near each other. For the equity-event feature, the measurement decision is whether financial
tone lives in exact list hits or in contextual similarity. The implementation is a set of four design choices. The
validation deliverable is performance on the tone task, not a high score on a generic analogy test.
Learning objectives. By the end of this note you should be able to:
- state the distributional hypothesis in the form used for embeddings;
- distinguish a one-hot type from a -dimensional embedding with below the vocabulary size;
- name the four design choices and the CBOW versus skip-gram objectives;
- say how a document vector is obtained, and which evaluation is the one that matters for a 10-K tone feature.
In this lesson
- From one-hot types to distributed vectors
- How the vectors are estimated
- From words to a filing
- Validation
- What you must record before the vector is a feature
Before you start
The full lesson, with worked examples and exercise solutions, is for members.
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