Parameter diagrams have grown in popularity by leaps and bounds in recent years. The more intensively they are used, the clearer the multiple benefits of this simple block diagram form become. The horizontal flow of the parameter diagram is the best start. The representation of the conversion functions of input variables into output variables is perfectly suited for the development of functional analysis.The vertical flow provides the best possible overview for identifying the noise factors. The variable control factors complete the character of the "Swiss army knife" for FMEA moderators.The clou to the good end: How are the "various jumping off points" from the parameter diagram into the phases of the FMEA designed in the best possible way.