workload simplified

[John Minor]

Vince: Did you have the full system installed? Who keeps the tanks filled?

John Minor
University of Illinois



On Thu, 2 May 2002, Vincent Earl Mrykalo wrote:

]Fred, et. al.,
]I would like to comment on the humidity variance factor.  I have found that
]before dampp chasers were installed in piano faculty studios, to adequately keep
]them in tune, I did full tunings on them every two weeks.  With the systems
]installed, I would go in every week and just tweak the tuning (10 min.), after a
]full tuning once per month.  We have humidity swings of about 30% on average.
]This works out to be 9 hours worth of work per semester before the dampp chaser,
]and 6 hours after it was installed.
]It seems to me that more than 30% humidity variance would not have necessarily
]increased the 9 hours, because the brunt of the changes would happen between
]seasons.  So I think that variances in humidity may have its limits.
]vince
]
]> Rather than weigh in on the current discussion, I think it would be
]> more fruitful if I explained the current workload formula in a bit of
]> detail. It's obvious from some of the comments I have read both on list
]> and privately that a large number of cauts don't really understand how
]> it works, and find it rather forbidding. I should probably have done
]> this last fall, but there's no time like the present. (Actually, there's
]> no time _but_ the present, but I'd better not get into that).
]> 	The formula begins with a base workload constant. In the current
]> Guidelines (which I will refer to as 1990 version), this number is 60.
]> In the proposed draft (2002 version), there is a choice of 40, 60, 80,
]> or 100. These are not arbitrary numbers. Rather, they are based on the
]> experiences of a large number of technicians over a period of decades.
]> There is a broad consensus that workloads in this range allow for
]> comprehensive maintenance of pianos in institutional settings over the
]> long haul.
]> 	The surveying I did last year (which didn't produce adequate responses
]> to produce what I was after at the time - a supplementary document
]> showing some real life numbers at real institutions; I haven't given up
]> on the idea, but it's on hold) reinforced the idea that these numbers
]> are good ones. Nobody with a workload over 100 thought the pianos were
]> being taken care of adequately. And within the range of 40 - 100 there
]> were examples of technicians who did think they were able to do an
]> adequate job under their particular circumstances.
]> 	I should note that the text of the 1990 version refers to workloads
]> between 40 and 80, and it is only in the workload formula that the
]> number 60 is adhered to. There is no reason 40 or 80 couldn't be plugged
]> into the 1990 formula.
]> 	This is fine as far as it goes, but we all know that there are many
]> variables which make circumstances enormously different from one
]> another. Exquisite climate control versus 70% plus swings; a brand new
]> inventory versus a 75 year old one; moderate use versus places where 16
]> plus hours hard playing per day is the norm. In other words, there are a
]> number of factors that increase or decrease the need for work, and they
]> have been pretty well identified in the 1990 formula (though there are
]> several quibbles with wording).
]> 	So the idea is to assign numbers to each factor which, multiplied by
]> the constant, will predict a reasonable workload under varied
]> circumstances. Let me take one factor in isolation to show how this
]> works. I'll choose humidity (climate control).
]> 	1990 version:
]> (1.00) Excellent: 10 percent maximum variance in relative humidity.
]> (0.90) Good: 20 percent maximum variance in relative humidity.
]> (0.80) Fair: 30 percent maximum variance in relative humidity.
]> (0.70) Poor: 40 percent maximum variance in relative humidity.
]> 	The first important thing to note here is which choice has the number
]> one next to it (1.00, excellent). The basic assumption under the 1990
]> version is that humidity must be controlled within 10% for the basic
]> workload to hold. Any greater variability will increase the workload. (1
]> x 60 = 60).
]> 	The second thing to note is how much increase is workload is assumed
]> for an increase in humidity variability. To take the extreme, it is
]> assumed that a 40% variance will allow a technician to take care of .70
]> as many pianos (70% if you prefer), or, using the 60 base, 42 pianos
]> (0.7 x 60 = 42). [Apparently conditions with variance in excess of 40%
]> are unheard of <g>.]
]> 	2002 version:
]> 1.3 - Excellent: 15% maximum variance in relative humidity (or has
]> humidity control unit installed and well-maintained)
]> 1.0 - Good: 30% maximum variance in relative humidity.
]> 0.7 - Fair: 50% maximum variance in relative humidity
]> 0.4 - Poor: Greater than 50% maximum variance in relative humidity
]> 	Note again where the one (1.0) is: this time at "Good, 30% variance."
]> In other words, this formula assumes that the base workload works at
]> institutions with 30% variance, and that it might be possible to have a
]> larger workload if humidity were controlled more tightly. How much does
]> this factor influence the workload as predicted by these numbers? Again,
]> to take the extremes, and using the same 60 as base, it predicts that,
]> for 15% maximum variance, one tech could manage 1.3 x 60 pianos (78),
]> while with greater than 50% variance, it predicts a tech could manage
]> only 0.4 x 60 (24) pianos.
]> 	In asking for feedback, I am asking whether these numbers are at least
]> close to reasonable. Are the percentages good ones? Should there perhaps
]> be more (eg, 10%, 25%, 40%, 55%, greater than 55%)? Are the multipliers
]> reasonable predictors of how much humidity variance affects workload?
]> (To compare, the 2002 version has a difference of over 3 to 1 between
]> excellent and poor, while the 1990 version has a difference of only 1.4
]> to 1).
]> 	This is pretty long, so I'll stop here. I'll come back at you with the
]> other factors at decent intervals.
]> Regards,
]> Fred Sturm
]> University of New Mexico
]