  Structure or projectional editors are a well-studied concept among
researchers and some practitioners. They have the huge advantage of preventing
syntax and in some cases type errors, and aid the discovery of syntax by users
unfamiliar with a language. This begs the question: why are they not widely
used in education? To answer this question we performed a systematic review of
57 papers and performed a bibliometric analysis which extended to 381 papers.
From these we generated two hypotheses: (1) a lack of empirical evidence
prevents educators from committing to this technology, and (2) existing tools
have not been designed based on actual user needs as they would be if
human-centered design principles were used. Given problems we encountered with
existing resources to support a systematic review, and the role of bibliometric
tools in overcoming those obstacles, we also detail our methods so that they
may be used as a guide for researchers or graduate students unfamiliar with
bibliometrics. In particular, we report on which tools provide reliable and
plentiful information in the field of computer science, and which have
insufficient coverage and interoperability issues.
