I did a quick internet search for advice on writing a dissertation methodology and came across some key points:
What if I want to find out about social trends, or the measurable effects of particular policies?
You will probably want to use large data-sets and undertake quantitative data analysis, and you will be adopting a realist approach to the topic studied. Quantitative dissertations are likely to be nearer to the lower end of the range of approved lengths for the dissertation (e.g. if the length is to be 5,000-8,000 words, dissertations based on quantitative analysis are likely to be closer to 5,000 words in length). They will also include tables and figures giving your important findings. Remember that all tables must be carefully titled and labelled and that sources of your data must be acknowledged.
'What if I want to record people's views on an issue, and give them a 'voice'?'
You will probably want to use in-depth qualitative data, and you may wish to adopt a realist, a phenomenologist, or a constructionist approach to the topic. Qualitative dissertations will include descriptive material, usually extracts from interviews, conversations, documents or field notes, and are therefore likely to be nearer to the upper limit of your word range (e.g. 8,000 words). The types of method suitable for a dissertation could include content analysis, a small scale ethnographic study, small scale in-depth qualitative interviewing and so on.
From this, I have concluded that qualitative primary research methods will prove most useful and effective for my dissertation project, as my topic is concerned with the contemporary, and therefore needs to be informed by contemporary views, opinions and thoughts from artists, designers and practitioners working in and responding to the now.
Through conducting a qualitative analysis, I will be likely looking to use at least some original material in the essay. This may be collected through in-depth interviews, participant observation recordings and field-notes, non-participant observation, or some combination of these.
I will also look to visit relevant exhibitions and art spaces to further my primary research, in order to gain a better understanding of my topic and gain a rounded perspective on contemporary graphic design practice and wider visual culture.