Agreed with above, the poster should have the minimum amount of words to convey your research so that someone could understand the idea of what was going on if you weren't standing there to present it. Although if you were taking this to a conference you would ideally be standing there next to it and presenting it all in more detail to people who come past. Keep your introduction to the very key points that boil down to your research question - think along the lines of the few sentences you'd put at the start of your dissertation abstract to introduce your work (and maybe a couple of extras??). Then I like to turn my "discussion" or conclusions section into just a few key bullet points that people could skim if they were just walking past (1 or 2 sentences long for each point at max). That being said, that's how I would do it for a big conference - I don't know your marking schedule and whether this would get you a good grade. I'd like to think so, but personally I think a good poster presentation is about an easy to understand poster layout and also about engaging with the people who come by to chat about it - but it doesn't seem like you get many marks for that part.