Who's doing this...?

The MIX program has been developed by Leon Bax, with assistance from many beta-testers and colleagues in clinical epidemiology, medical statistics, and medical informatics. For the work on version 2.0 and versions after that, I hope to find one or two co-developers that can assist with program development, website maintenance, and methodological research in meta-analysis.

Development goals

Even though numerous researchers in health care are confronted with or involved in meta-analyses, there is a lack of software that can aid researchers in their learning phase. Existing software that is modern, both in terms of interface and in terms of computational and graphical options is often commercial and can be rather expensive. Our primary objective in the starting phase of the MIX project was to develop a free but comprehensive program for meta-analysis that could be applied in both analytical and educational settings. Because meta-analyses are still most often done with data from causal studies (therapeutic trials as well as etiologic cohorts and case-control studies), we decided to focus, at least initially, on causal meta-analysis.

Development

Before the actual development, we made an inventory of the most important meta-analytical tests and approaches, and brainstormed on ideas for an interface. Because the program was to be free, development and maintenance had to be relatively easy and quick. Therefore, our a priori idea was to use the Visual Basic Editor of Excel and create an Excel add-in. Although a rather unorthodox approach in this area (all existing meta-analysis programs are stand-alone programs and work independently of Microsoft Office), Excel provides a sophisticated calculation and graphics platform that is well-suited to many meta-analytical methods and at the programmer's disposal before any programming is done.

Since we wanted to move beyond the occasional spreadsheet that can perform meta-analytical calculations, we started by designing a programming structure in which the already existing Excel functionality could be exploited to its maximum. Sophisticated procedures were custom-programmed with Visual Basic in the Visual Basic for Applications (VBA) editor of Excel 2003 (and tested in Excel 2000 and onward). The so-called front-loader (a start-up program initiated with an icon) and some small assistant programs (all being non-Excel entities) were developed with Visual Basic 6.0 (VB6). To increase program stability and prevent users from accidentally altering the Visual Basic procedures, the source code cannot be accessed while the program is running.