In the upper left corner you can define “Shift for average calculations”. This means, that you can define a timeframe in which you always assume that values are correct. As an example, you can imagine a three shift production process. Depeding on orders, it can happen that the afternoon and night shift are cancelled from time to time. However, the morning shift will always be carried out. In this case, you could define the shift start of 06:00 am and a shift end at 02:30 pm as depicted below.
All other calculated values will not be considered for the average and standard deviation calculation. If you want to include all values, you must set it up from 12:00 am to 11:59 pm. This is also depicted below.