Forensic scientists' conclusions: how readable are they for non-scientist report-users?

Scientists have an ethical responsibility to assist non-scientists to understand their findings and expert opinions before they are used as decision-aids within the criminal justice system. The communication of scientific expert opinion to non-scientist audiences (e.g., police, lawyers, and judges) through expert reports is an important but under-researched issue. Readability statistics were used to assess 111 conclusions from a proficiency test in forensic glass analysis. The conclusions were written using an average of 23 words per sentence, and approximately half of the conclusions were expressed using the active voice. At an average Flesch-Kincaid Grade level of university undergraduate (Grade 13), and Flesch Reading Ease score of difficult (42), the conclusions were written at a level suitable for people with some tertiary education in science, suggesting that the intended non-scientist readers would find them difficult to read. To further analyse the readability of conclusions, descriptive features of text were used: text structure; sentence structure; vocabulary; elaboration; and coherence and unity. Descriptive analysis supported the finding that texts were written at a level difficult for non-scientists to read. Specific aspects of conclusions that may pose difficulties for non-scientists were located. Suggestions are included to assist scientists to write conclusions with increased readability for non-scientist readers, while retaining scientific integrity. In the next stage of research, the readability of expert reports in their entirety is to be explored.