During my PhD, I kept all the pens that I have finished. There was not much thinking at the beginning, but when the numbers started getting significant I though it could be a fun and useless statistics I could easily keep record.
On my last day I took a picture with them, having a bar graph in mind. I forgot about it, and now, almost 2 years later and with timing for posting long time gone, I have crossed the images once more when cleaning my hard drive. Finally, I present my use of pens.
In total, there are 9 pens: 7 black, 1 blue and 1 red. Naturally, they do not represent the totality of pens I have used when working over the 3 years of my PhD, they are the ones that I have used on a daily basis and have completely deprived from ink. As you can see, I’m more a gel than a ballpoint kind of guy, as I fell that the latter does not really leave a trail of what is being written. The same motivation is used for favoring the color black, after realizing that blue is not really as readable to me. Blue and red were only used in revisions or at the time I draw diagrams.
Legal number of working hours per year in France is of 1607, this means that during my 3 years as a PhD student (4821 hours) I consumed 0.00186 pens per hour, or 0.01307 a day. On average, 537 hours were necessary to finish a pen, 3 per year. I have no idea if my consumption was too small or the opposite and I leave it here hoping that this random stat I tracked may interest anyone.