Passive voice is often used in scientific writing for several reasons:

1. Objectivity and Neutrality: The use of passive voice helps to maintain an objective and neutral tone in scientific writing by shifting the focus from the researcher or author to the research itself. This can help to avoid bias and make the writing more impartial.

2. Focus on Processes and Results: Passive voice allows writers to emphasize the processes and results of the research rather than the individuals conducting the research. This can be particularly useful in scientific writing where the focus is on presenting findings and data.

3. Depersonalization: By using passive voice, statements can be depersonalized, meaning that the emphasis is placed on the action or outcome of the research rather than on the individual or group carrying out the research. This can lead to a more professional and formal tone in scientific writing.

Overall, passive voice is considered an effective choice in scientific writing because it helps to maintain objectivity, neutrality, and a focus on processes and results, while also depersonalizing statements and highlighting the action or outcome being discussed.