Wikipedia definition:
Root cause analysis (RCA) is a class of problem solving methods aimed at identifying the root causes of problems or events. The practice of RCA is predicated on the belief that problems are best solved by attempting to correct or eliminate root causes, as opposed to merely addressing the immediately obvious symptoms. By directing corrective measures at root causes, it is hoped that the likelihood of problem recurrence will be minimized. However, it is recognized that complete prevention of recurrence by a single intervention is not always possible. Thus, RCA is often considered to be an iterative process, and is frequently viewed as a tool of continuous improvement.

RCA, initially is a reactive method of problem solving. This means that the analysis is done after an event has occurred. By gaining expertise in RCA it becomes a pro-active method. This means that RCA is able to forecast the possibility of an event even before it could occur.

Root cause analysis is not a single, sharply defined methodology; there are many different tools, processes, and philosophies of RCA in existence. However, most of these can be classed into five, very-broadly defined "schools" that are named here by their basic fields of origin: safety-based, production-based, process-based, failure-based, and systems-based.

* Safety-based RCA descends from the fields of accident analysis and occupational safety and health.
* Production-based RCA has its origins in the field of quality control for industrial manufacturing.
* Process-based RCA is basically a follow-on to production-based RCA, but with a scope that has been expanded to include business processes.
* Failure-based RCA is rooted in the practice of failure analysis as employed in engineering and maintenance.
* Systems-based RCA has emerged as an amalgamation of the preceding schools, along with ideas taken from fields such as change management, risk management, and systems analysis.

Despite the seeming disparity in purpose and definition among the various schools of root cause analysis, there are some general principles that could be considered as universal. Similarly, it is possible to define a general process for performing RCA.

http://en.wikipedia.org/wiki/Root_cause_analysis

In cazul unei situatii nedorite, consumatoare de resurse si care tinde sa se repete, exista posibilitatea ca gasirea si inlaturarea cauzei reale (denumita Cauza-Radacina) a acestei situatii sa se repercuteze benefic asupra activitatii pe care o influenteaza, in asa fel incat situatia sa nu se mai repete. Aceatsa metoda este denumita Analiza Cauzei-Radacina si consta in gasirea cauzei reale a unei probleme si rezolvarea acesteia mai curand decat continuarea incercarii de a inlatura simptomele (efectele).