Polyhedrika

When a process variable has only random variation, each output is independent of the previous ones.This is what happens in a lottery. In some processes this independence does not happen.   If we control our daily weight, for instance, our weight today is correlated to the weight of the previous days: it has autocorrelation . Weight Autocorrelation One common case of autocorrelation is shown by our body weight.  Our weight today is correlated with: Yesterday's weight:      53% The day before:           39%    Body weight has inertia: you don't expect sudden changes. A similar effect happens when you control a heavy aircraft or a ship: its masive weight prevents you from making a sharp turning or make a sudden stop.  This opposing force to change is what is called Inertia . This inertia definition applies to moving objects and it is proportional to the object mass.  Inertia also applies to fluids: a tank accumulating ...

  Data collection is not for free. While an operator is recording data, he/she is not producing. In general variable data such as a speed, temperature, etc. requires some sort of equipment to measure it and therefore it is more expensive to collect than attribute data: Pass/Fail, On-time/Late, etc. Time is a key variable in any process which can automatically be collected by any PC, Portable, Tablet or Smartphone, therefore it does not require any additional measuring equipment. Entering a date or a time manually into a terminal is prone to multiple typing errors which if undetected can distort all subsequent key metrics. If data is collected on paper and then typed into the system at a later stage, apart from the waste of this operation, the errors might be difficult to recover. If we are able to simplify the data recording operation, the operator can report in real time all incidents or data entries, in which case the data collection application can automatically associate a Tim...