When writing scientific research proposals I have been advised to try and stick to active voice because passive tends to sound indirect and to imply doubt. However, when writing in active voice, I find it difficult to not use personal pronouns. Does anyone have any tips for maintaining active voice without using personal pronouns?
Well, if you're that bothered about avoiding personal pronouns, you can always say "The author", "The researcher" etc. It's really a matter of preference; not all scientists think there's anything terribly wrong with good old-fashioned words like "I" and "we"...
You may also want to see if you can actually find a scientific study attesting to the perceived indirectness or doubt of the passive.
This is an old question, but I was looking for new tips so I'll add a few of my own for the benefit of other readers.
When we use personal pronouns in scientific writing, we're trying to either emphasize that we did something cool (as in a journal paper) or that we're going to do something cool (as in a proposal).
For a paper, it would read something like, "we developed a model of system resiliency that improves ..." Even though your purpose in writing the paper is to show off what you accomplished, the reader's purpose to learn about the model and its properties. In that case, you'd re-write the paper to talk about what the model can do rather than that you made a model. Sometimes this is hard to do because you've probably thought about this in terms of your own actions and tasks for a long time. The final result would be something like "The model has three primary analytical uses, the first of which improves ..." It should allow you to write in more detail about the cool thing you did and generally use fewer words to do so.
In the case of writing a research proposal, a sentence would read something like "We plan to reduce the number of defects in the XYZ process to ..." Again in this case, you're talking about what you are going to do, which is somewhat more appropriate for a proposal, but the reader / evaluator wants to learn about the research plan as quickly as possible so he or she can decide if it's sound and feasible. You can use the research plan, sub-tasks in the plan, and their properties as subjects of your sentences. This would go something like "Work under Task 1 will reduce defects from 42% to 22% in milestone A."