The thing to watch out for there that I thought of is that the longer the growth period, the more hair will be lost outside of the sample collection area due to natural fallout and everyday abrasion. Probably not much, but we won't know that for sure without experimentation ...
(If I undertand hair growth correctly, sometime after a hair has grown as far as it's going to and sat there for a while, it'll spontaneously fall out before the follicle starts a new one ... right? So presumably even if all that's grown out is a fraction of an inch of stubble, some substantial fraction of those [what's the simple noun that 'stubble' is a collective for?? 'Stub'?] stubs will be ready to fall out while the subject is going about his or her extra-lab activities. So unless I plan to spend the entire duration of the experiment in a controlled environment where everything that falls off my body is collected -- presumably naked the whole time both to minimize friction-induced losses and to avoid contaminating the samples with fibers rubbed off of clothing -- at some point incidental extra-laboratory loss of sample will may become significant. But I don't know how long an intra-shaving interval makes the extra-lab losses enough to worry about.)
Another caution brought up by the Sheepie on the phone: hair growth rate is also going to be affected by hormonal fluctuations, cyclic and otherwise, and possibly also by the weather. So to get a good average, the entire experiment, including varying the intra-shave interval, will need to be repeated several times.
The more I think about this, the more I like the idea of coercing grad students into it.
a caveat ... oops, two
(If I undertand hair growth correctly, sometime after a hair has grown as far as it's going to and sat there for a while, it'll spontaneously fall out before the follicle starts a new one ... right? So presumably even if all that's grown out is a fraction of an inch of stubble, some substantial fraction of those [what's the simple noun that 'stubble' is a collective for?? 'Stub'?] stubs will be ready to fall out while the subject is going about his or her extra-lab activities. So unless I plan to spend the entire duration of the experiment in a controlled environment where everything that falls off my body is collected -- presumably naked the whole time both to minimize friction-induced losses and to avoid contaminating the samples with fibers rubbed off of clothing -- at some point incidental extra-laboratory loss of sample
willmay become significant. But I don't know how long an intra-shaving interval makes the extra-lab losses enough to worry about.)Another caution brought up by the Sheepie on the phone: hair growth rate is also going to be affected by hormonal fluctuations, cyclic and otherwise, and possibly also by the weather. So to get a good average, the entire experiment, including varying the intra-shave interval, will need to be repeated several times.
The more I think about this, the more I like the idea of coercing grad students into it.