Reports that are primarily analytical usually require conclusions. These are sometimes combined with recommendations. Proposals often use conclusions to provide a final word to the readers (i.e. the potential donors) because having an impact at the end of the proposal is important. You can also improve executive summaries and large sections of major reports by including conclusions. With some long reports, a conclusion may take up an entire section or chapter of the report. In cases like this, you will often also see conclusions for each chapter.
The conclusion enables you to reinforce the main messages of the document. A conclusion summarizes the report as a whole, drawing inferences from the entire process about what has been found, or decided, and the impact of those findings or decisions.
Even in a short report, it is useful to include a conclusion. A conclusion demonstrates good organization. When written well, it can help make the reader’s task easier. With a good conclusion, you can pull all the threads of the report details together and relate them to the initial purpose for writing the report. In other words, the conclusion should confirm for the reader that the report's purpose has been achieved.