After two years of data collection, or a minimum of 20 data points, the control chart should be maintained using only the 20 most recent data points.
By using the most recent 20 data points, the control chart will be accurate and maintained.
Founded by the ancient Romans, the city has a proud soldiering history, giving the Venetian Republic a famous condottiere, Bartolomeo Colleoni, and the largest contingent in Garibaldi's 1,000 Red Shirts.