Graphic Representations

A few days ago Eugenio Capodacqua published on his website sportpro.it a nice article entitled "Così la zona ha cambiato anche la mia vita". (That’s how the ‘zone’ changed my life too). 
The Author proposes a graphic representation of the variations in his body weight and fat % from 10/7/2010 until 22/11/2010. 

The weight data shows physiological obscillations, up to 2 kg within 2-3 days, that could only be explained as variations in body water content (by the way, it would be very interesting to see the variations in Hb values too…). 

The values in body fat % present variations in consecutive days, posing doubts on the reliability of the measurements. 

But that is not what caught my attention; rather it was the way the line was traced in joining the first and the last weight measurements. 
It is a straight line that does not really reflect the temporal fluctuation of this parameter, simply joining 2 values, the highest and the lowest, picked by the Author. 

The progress of the body weight as a matter of fact shows a significant decrease from the 10th of July until the end of September, further stabilizing or slightly increasing again, although the Author chooses to end the line on a low value (72.8 kg in 22/11), conveniently to his representation. 
What is the reason for not ‘landing’ the line over the weight value of 2 days earlier (74.5Kg in 20/11)? 

I am not questioning the effects of the zone diet on health and weight loss, but merely pointing out how the way a graph is presented could mislead, not always in good faith, into wrong or inexact conclusions. 

Moreover, back in September, Capodacqua posted on his website another interesting article (later removed…): "Ecco come il passaporto 
Bio inchioda chi si dopa" (How the Bio Passport nails dopers), in which he presented graphics (borrowed from the Cycling Pro magazine) displaying some hematologic parameters of professional riders De Bonis and Caucchioli. 

Notwithstanding some mistakes in the captions, I will refrain from going into the merits of the valuation of such values, but once again I’d like to point out how the graphing method proposes the simple succession of the numbers, utterly ignoring the time elapsed between the tests or the period of the year in which the samples were taken. 

Such way of graphing cannot but bring to mind the graphic representations proposed by the experts of public prosecutor Giovanni Spinosa about the hematocrit variations of my patients-athletes back in the ‘90s. 
But that is a different story.

03 Dec 2010