Process Door refers to the analysis of the process to identify the causes of the problem by using the process map based tools.
Data Door refers to the analysis of the data to identify the causes of the problem by using graphical or statistical tools.
An application-oriented question on the topic along with responses can be seen below. The best answer was provided by Sanat Kumar, Natwar Lal and Sudheer Chauhan. Congratulations to all the winners.
Also review the answer provided by Mr Venugopal R, Benchmark Six Sigma's in-house expert.