Please show your work and label your units

A small rant on units. I have run into meaningless use of units so often lately that I thought I post a small rant here. “Please show your work and label your units” is something every instructor I had since grade school has been reiterating, so why do we have a problem with people failing to do just that? Units are important as they provide understanding to numerical measurements. To do so the units used in quantitative measurements should be appropriate for what is measured, consistent with comparable measurements, and above all well labeled. To begin with I would like to address the disturbingly prevalent absence of units. For example I was recently looking at a simple matrix chart in a magazine comparing baby monitors. One of column was labeled distance and had units such as 700, 300, 500, but no where in the article or the chart did it tell you 500 what; inches, meters, feet, miles, what? The second frustrating error is the inconsistent use of units. To use the prior example I would have only slightly less disdain if the article indicated 700 In., 300 M, 500 Ft. Yes, one now has the information required to understand the measurement and to do the comparison, with conversion, however the inconstant units do not allow us to use the chart in a useful way to make quick comparisons. The third issue I have is the use of units that either don't make sense for the measurement or don't convey accurate information. Simple said units need to make sense for what the measure. For example, the axiom that one should always leave two car lengths between your car and the car ahead of you, suffers from this bad choice of units. The units, car lengths, are first non standard (i.e ranging 2.7 M for a Smart to 5.7M for a Lincoln Town Car) and second, meaningless. I say meaningless because stopping distance is a function of the speed the vehicle is traveling. For example if I am travailing at 10 kph I can easily stop in less then 3 meeter's. However if I am travailing at 150 kph I would not be able to register the need to stop and have my foot hit the break, let alone stop, inside 5 times that distance. Let us look at it this way, we want a fixed unit to govern distance with regard to a variable distance/time function; thus we need a constant time unit. Simply said, if you stay two seconds behind the car ahead of you the distance will become greater at higher speeds, thus accommodating for the greater stopping distance required.
Now I understand when what you are looking to measure quantitatively is intrinsically tied to a qualitative value it gets harder. For example a recruiter asked me how many years of experience I have writing disaster recovery plans. My first thought was, who does nothing but write disaster recovery plans for their career, that must be a rather specialized market. I was tempted to say 10 years since my first disaster recovery project was in 1998, when I took over a flawed DR project, and the last one I wrote was in 2008 when I wrote one as part of developing standard operational documentation. However the first plan was for an environment I understood with a budget I understood and was limited in scope (servers and licenses for the IT department which served a greater college at the local university) and the last one was integrally tied to the development of a brand new .com operational procedures manual which I was helping start from scratch. And while I had written several in between, (~5 in total) they had all been part of normal operations for the company and not separately measured. In addition many of those had the assistance of an establish continuity plan to borrow from. I would argue hours, not years, would have been a more accurate reflection of my experience. For example if you have two candidates, one of which has 10 years experience, and one who has 2 years, which one should you higher for a managerial position? What if the one who has 10 years managed one worker who clocked only 8 hours a week for 10 years while the second one managed a department of 50 full time employees and a dozen contractors for two years? One has more “years” but at the same time far fewer hours of managerial experience. However, this is nearly an impossible paradigm shift for most people. In the above example if I had replied to the recruiters experience query with “I have over 2,500 hours of disaster recovery experience” it is likely I would have received a blank stare.
In conclusion, please use appropriate, consistent, and well labeled units in all quantitative measurements. Doing so will make your work measurably more useful.