Each of the DIPEx modules is collected and analysed by an experienced and trained researcher who specialises in this sort of study. Our researchers are social scientists by training with backgrounds in sociology, anthropology or history. We have a careful recruitment process to ensure that we appoint excellent and sensitive researchers. Before the researchers start interviewing they read published books and papers on the subject to help identify issues for the interviews and to find out what sorts of people we need to include in the study.

'Who We Invite to Take Part in the Study' packs, which include a 'patient information sheet', an introductory letter, a reply slip and stamped addressed envelope are given to potential participants by their GPs, hospital consultant or a member of their support group. Sometimes people hear about the study and contact us directly, in which case we send them a pack to help them decide if they want to take part. To make sure that a wide range of experiences and views are included we use a method called purposive (or maximum variation) sampling (Coyne, 1997). The specialist advisory panel (patients, health professionals and researchers) for each of the studies help us to ensure that we have included all of the main treatments, perspectives and types of patient. We carry on collecting interviews until we are convinced that we have represented the main experiences and views of people within the UK. Often this requires between 40 and 50 interviews.

The interviews
The interviews take place throughout the UK, mainly in respondents' homes. If people prefer they can be interviewed somewhere else. Interviews are usually sought with people on their own, but sometimes a partner or friend may be present during the interview. All the interviews are audiotaped for analysis. If the respondent is happy to consent, interviews are also recorded on digital videotape. In the first part of the interview people are asked to tell the story of what has happened to them, from when they first began to suspect there was a problem. When the story has finished the researcher may ask additional semi- structured questions, identified from the review of the literature.

Analysis
The interview tapes are fully transcribed, and each transcript is returned to the respondent for review. Participants sometimes decide that there are sections of the interview they would rather did not appear on the website, in which case the researcher removes them from the final version. A computer assisted software package called QSR N6 is used to help organise the interview transcripts for analysis. Analysis begins soon after the first interview (Tesch 1990).

Before analysis starts we draw up a list of categories for analysis, and these are identified from the literature and from the first few interviews that have been done, but as the analysis progresses additional categorises are added.

During the analysis we link sections of text from one interview with sections of text from the other interviews that cover a similar topic. When the analysis is finished we can then look at what everyone has said about a particular topic.

Two members of the DIPEx research team discuss the emerging themes and new hypotheses may be suggested. This may lead to changes in the interview guide for subsequent interviews, which also leads to a change in analysis, with the addition of more categories.

During analysis two members of the DIPEx team look at the QSR N6 'reports' and together they make sure that important points have been included in the topic summaries (see below). At this stage there may be some discussion about meaning and interpretation of points made during the interviews.

Copyright
After reviewing the transcript (if they wish to) the respondent is asked to sign a copyright form for inclusion of their interview on the website.

Writing the topic summaries for the site
Two qualitative researchers from the DIPEx team look at the interview transcripts for the study and discuss which topic summaries should be written for the site. The list of topics is also discussed with the advisory panel. Each topic summary is drafted by the researcher, checked by a senior DIPEx researcher, revised and then sent to an appropriate member of the advisory panel for additional contextual material and checking.

Selecting the clips for the site
The researcher identifies video, audio and written clips from the interviews to illustrate the range of views and experiences in the interviews.

Publishing papers from DIPEx studies
We aim to publish two or three papers in peer reviewed journals from each of the DIPEx studies. These are sent to social science and specialist and general medical journals. We regard this as an important way of disseminating our results -widely to all types of professional readers as well as ensuring that the quality of the studies is maintained.

References
Coyne, I. (1997) Sampling in qualitative research. Purposeful and theoretical sampling: merging or clear boundaries? Journal of Advanced Nursing, 26, 623-630.

Tesch, R. (1990) Qualitative research. Analysis types and software tools. Basingstoke: Falmer Press.

QSR International Pty, QSR N5, QSR International Pty, Melbourne, Australia.