Barooah wasn’t about to try to answer a question like this with guesswork. He had a good data set that showed how many minutes he spent each day in focused work. With this, he could do an objective analysis. Barooah made a chart with dates on the bottom and his work time along the side. Running down the middle was a big black line labeled “Stopped drinking coffee.” On the left side of the line, low spikes and narrow columns. On the right side, high spikes and thick columns. The data had delivered their verdict, and coffee lost.
Lookie! I made a graph and it shows something! It MUST be causation, there is no other explanation.
Adding manpower to a late software project makes it later. -- F. Brooks, "The Mythical Man-Month"