Research in Complex Systems:
While completing a Ph.D. in Science Education, the author of this page was priviliged to be assigned a reading course on Systems Theory as a part of his program, starting with a book,"General Systems Theory" by Ludwig Von Bertalanffy
General Systems Theory looks at similarities across scientific disciplines, to ascertain principles that are applicaple to all systems. A "Systems Approach" analizes systems wholistically, looking for tools and techniques for solving the problems of particular systems. Bertalanffy, an Austrian Biologist, naturally saw application analysing the ecosystem that supports all life on earth. To say that the book and the reading course of which it was a part was transformative, is an understatement!
Yet in a science world that is both complex and highly departmentalized, taking a general systems viewpoint is difficult. Much of our research is designed from the outset to reduce complexity, and to ignore any variables that we deem unimportant and/or difficult to measure. So we often resort to what I refer as the "agricultural plot model" and use tools like analysis of variance (ANOVA), comparing the means of two or more groups to see if they are significantly different from each other to support a hypothesis.
In part, widespread use of ANOVA was dictated by the computational abilities of the time, but even then there were computation tools to support Factor Analysis, which by design allowed for many more variables, by measuring their respective contribution to overall variance of the issue under study.
For example, we often talk about species loss in terms of loss of habitat, disease, reproductive problems, competition from other species, pollution, agricultural chemicals, and so forth. I have yet to see this quantified for any species by a factor analsis that attempts to determine the relative importance of each of these major factors..