PMI e–learning – summary
Today I finished the PMI e-learning course. To be honest I was familiar with all of the tools they introduced but what I liked in there was that they showed how their cycle can be used for an improvement. The example was of course very simple and not very extended, however it delivered the message. Long story short - there were some interesting bits (connected mainly with leadership and proper process approach) which were beneficial.
However, this is not the case of the entry. What I wanted to share with you is how I understood 'process capability' index more thanks to PMI. The story is:
While going throught Lesson 14 about Cp. There was a formula for that and although it's just one line I was shocked when their Cp turned out to be 0,33! In my mind I started wangling with data to get a better Cp ofc! Calculations in the denominator were 42 - 10 (min) so I thought it Cp would be better if we had sth like 40 - 28 (min). I realise that those values are from control limits from a chart so we cannot just assume them, however if we happened to have CL between 28 and 40 min instead of 42 and 10 then our Cp would be better. OK one will say it's logical since the limits are closer so there is less variation (or spread?) so Cp is higher in the first case. BUT now this means that if we deliver pizza in less than 28 min (i.e we had a case of 10 min delivery) if we looked at Cp it shows our performance is very very poor!!! So it seems like the later we deliver (to a certain extent) we will get better Cp!!! Now that's not what we want - is it?? We are fighting with late deliveries issue and the better we are the worse Cp is????? Now that was a nice question and I wrote it down to discuss it in the class.
But then moving on in Lesson 21 they came back to Cp case and they seem to provided an answer to my question. This is what I figured out:
They improved their delivery to 20 min time (on average) so Cp improved as well (like I had assumed). But then the answer came with the strike: Cp was better (but still less than 1!) because the process's average was shifted (from Specification limits) so it was still underperforming. So now their delivery time is better but I understand why it's still not good (though at first most of us would say that reducing delivery time (as much as possible) would help with the 'late delivery issue'. Well not really it turns out! Now that's a lesson!!! On the other hand, this showed that I forgot about CUSTOMER REQUIREMENTS....).
Now this seems to be a broader subject and I hope I'll come across more such cases and issues so that I'll be able to analyse it and learn. Hopefully during this module I'll get that!!! Can't wait.