Question: What their model can be used to do?
Evidence: Extracting data elements such as study descriptors from publication full texts is an essential step in a number of tasks including systematic review preparation BIBREF0 , construction of reference databases BIBREF1 , and knowledge discovery BIBREF2 . These tasks typically involve domain experts identifying relevant literature pertaining to a specific research question or a topic being investigated, identifying passages in the retrieved articles that discuss the sought after information, and extracting structured data from these passages. The extracted data is then analyzed, for example to assess adherence to existing guidelines BIBREF1 . Figure FIGREF2 shows an example text excerpt with information relevant to a specific task (assessment of adherence to existing guidelines BIBREF1 ) highlighted.
Extracting the data elements needed in these tasks is a time-consuming and at present a largely manual process which requires domain expertise. For example, in systematic review preparation, information extraction generally constitutes the most time consuming task BIBREF4 . This situation is made worse by the rapidly expanding body of potentially relevant literature with more than one million papers added into PubMed each year BIBREF5 . Therefore, data annotation and extraction presents an important challenge for automation.
A typical approach to automated identification of relevant information in biomedical texts is to infer a prediction model from labeled training data – such a model can then be used to assign predicted labels to new data instances. However, obtaining training data for creating such prediction models can be very costly as it involves the step which these models are trying to automate – manual data extraction. Furthermore, depending on the task at hand, the types of information being extracted may vary significantly. For example, in systematic reviews of randomized controlled trials this information generally includes the patient group, the intervention being tested, the comparison, and the outcomes of the study (PICO elements) BIBREF4 . In toxicology research the extraction may focus on routes of exposure, dose, and necropsy timing BIBREF1 . Previous work has largely focused on identifying specific pieces of information such as biomedical events BIBREF6 or PICO elements BIBREF0 . However, depending on the domain and the end goal of the extraction, these may be insufficient to comprehensively describe a given study.
Therefore, in this paper we focus on unsupervised methods for identifying text segments (such as sentences or fixed length sequences of words) relevant to the information being extracted. We develop a model that can be used to identify text segments from text documents without labeled data and that only requires the current document itself, rather than an entire training corpus linked to the target document. More specifically, we utilize representation learning methods BIBREF7 , where words or phrases are embedded into the same vector space. This allows us to compute semantic relatedness among text fragments, in particular sentences or text segments in a given document and a short description of the type of information being extracted from the document, by using similarity measures in the feature space. The model has the potential to speed up identification of relevant segments in text and therefore to expedite annotation of domain specific information without reliance on costly labeled data.
We have developed and tested our approach on a reference database of rodent uterotropic bioassays BIBREF1 which are labeled according to their adherence to test guidelines set forth in BIBREF3 . Each study in the database is assigned a label determining whether or not it met each of six main criteria defined by the guidelines; however, the database does not contain sentence-level annotations or any information about where the criteria was mentioned in each publication. Due to the lack of fine-grained annotations, supervised learning methods cannot be easily applied to aid annotating new publications or to annotate related but distinct types of studies. This database therefore presents an ideal use-case for unsupervised approaches.
While our approach doesn't require any labeled data to work, we use the labels available in the dataset to evaluate the approach. We train a binary classification model for identifying publications which satisfied given criteria and show the model performs better when trained on relevant sentences identified by our method than when trained on sentences randomly picked from the text. Furthermore, for three out of the six criteria, a model trained solely on the relevant sentences outperforms a model which utilizes full text. The results of our evaluation support the intuition that semantic relatedness to criteria descriptions can help in identifying text sequences discussing sought after information.
There are two main contributions of this work. We present an unsupervised method that employs representation learning to identify text segments from publication full text which are relevant to/contain specific sought after information (such as number of dose groups). In addition, we explore a new dataset which hasn't been previously used in the field of information extraction.
The remainder of this paper is organized as follows. In the following section we provide more details of the task and the dataset used in this study. In Section SECREF3 we describe our approach. In Section SECREF4 we evaluate our model and discuss our results. In Section SECREF5 we compare our work to existing approaches. Finally, in Section SECREF6 we provide ideas for further study.
Therefore, in this paper we focus on unsupervised methods for identifying text segments (such as sentences or fixed length sequences of words) relevant to the information being extracted. We develop a model that can be used to identify text segments from text documents without labeled data and that only requires the current document itself, rather than an entire training corpus linked to the target document.
Answer: To identify text segments from text documents without labeled data and that only requires the current document itself, rather than an entire training corpus linked to the target document.