NWCRU
Collection Profile
The Key approach in attempting to estimate the three areas of cost (Storage,
Documentation and Conservation) that an institution is likely to incur, is to closely
examine its Collection Profile. This gives the overall pattern of its Natural History
holdings and even a cursory glance at the specimen numbers in each category, will show
where the strength of the collections lie. Figure 1 shows such a profile for Saddleworth
Museum (Class B39) in Oldham.
Figure 1 - Institution: Saddleworth Museum
The following data shows the collection profile (the estimated number of specimens in each
of seventeen categories) for the above institution.
Code Specimens
Category
01 56 Taxidermy Mounts
02 0 Vertebrate Skins
03 16 Osteological
04 2,001 Oological
05 250 Entomological
06 0 Molluscan
07 0 Other Invertebrates (Dried)
08 0 Spirit Preserved
09 0 Microscope Slides
10 0 Herbarium Sheets
11 0 Other Botanical (Boxes...etc)
12 0 Biological Models
13 50 Rocks
14 119 Minerals
15 162 Fossils
16 31 Other Geological
17 0
Archival Material
Specimens Total: 2,685
There are a disproportionate number of Oological specimens (75%), as opposed to
geological (13%), entomological (9%), taxidermy (2%) and Osteological (1%). Consequently,
any method for approximating the cost of Storage, Documentation and Conservation (S+D+C)
for an institution, must reflect such collection biases. The most straightforward way of
achieving this is to use weighted means, which maintain the pattern of collection
strength. This was particularly important for estimating Conservation and Storage costs,
where costs per-specimen can vary dramatically between different categories within the
collection.
There is however a danger here and it is important to stress to the reader and user of
this North West Collections data that figures for costings are estimates. The use of
simple statistical methods for summarising and estimating, does not confer Biblical truth.
Instead figures should be viewed as guidelines, to assist curators in assessing a) whether
their desired collections management policy is likely to cost thousands, tens of
thousands, or hundreds of thousands of pounds, or b) whether acquisition, transferral,
rationalisation, storage, or conservation of a collection would be cost effective.
The overall approach has been to develop costs on a per-specimen basis, as opposed to
the less informative person-hours measure. Institution collections are comprised of
specimens and specimen numbers or categories are often used to compare institutions
(whether rightly or wrongly). Hence it seems sensible to compute cost on a specimen basis.
If the number of specimens in an institution is known, or can be estimated, then so can
the cost of housing, documenting and conserving that number, or some percentage of it.
Storage Costs
Table 1 shows the average cost of storing a specimen and the type of storage for each
of the Natural History Categories. Cabinet prices vary, but those shown are recent figures
obtained during August '93-94 from curatorial staff at Liverpool Museum (A59).
Table 1 - Information on Storage Costs
Key: d = Drawer, c = Cabinet, b = Peg Board
Code Average Storage Category Storage Unit Spp Per Unit Cost
cost per Unit
Specimen
01
£2.50
Taxidermy Mounts
Peg
Boards 50
4b=1c
@ £500
02 £1.25 Vertebrate Skins Drawers 20 20d=1c @ £500
03 £2.77 Osteological Drawers 12 15d=1c @ £500
04 £0.11 Oological Drawers 100 45d=1c @ £500
05 £0.67 Entomological Drawers 100 15d=1c @ £1000
06 £0.13 Molluscan Drawers 100 15d=1c @ £200
07 £0.33 Other Invertebrates (Dried) Drawers 30 20d=1c @ £200
08 £0.29 Spirit Preserved Drawers 70 20d=1c @ £400
09 £0.20 Microscope Slides Drawers 36 28d=1c @ £200
10 £0.49 Herbarium Sheets Shelves 60 12s=1c @ £350
11 £1.71 Other Botanical (Boxes, etc) Drawers 50 14d=1c @ £1200
12 £1.67 Biological Models Shelves 50 6s=1c @ £500
13 £0.96 Rocks Drawers 40 26d=1c @ £1000
14 £0.96 Minerals Drawers 40 26d=1c @ £1000
15 £0.96 Fossils Drawers 40 26d=1c @ £1000
16
£0.96
Other Geological
Drawers
40
26d=1c @ £1000
1. This category refers specifically to any botanical material which is not stored specifically as herbarium sheets. For example, boxed and packeted items.
2. This category includes: Sections, Drill Cores and...etc.
Storage costs are, as one would generally expect, directly proportional to the size of
the object being stored. Hence small specimens located among categories Oology to
Herbarium Sheets (Codes 4 - 10) are relatively cheap to house (mean cost per specimen =
£0.32). Geology tends to be more expensive by a factor of at three and costs about £1
per specimen (mean cost per specimen = 0.96). Large and bulky objects such as Taxidermy
Mounts, or Other Botanical ... etc. (Codes 1, 2, 3, 11 & 12), cost around £2
per-specimen (mean cost per specimen = £1.78) to store.
In addition of course, drawer space in cabinets is never used optimally. There are
always blank spaces due to the fact that specimens are stored according to some taxonomic
arrangement. Thus the cost of storing small, medium and large items need to be modified
accordingly. The figures in Table 2 illustrate this. They have been obtained by randomly
sampling the contents of cabinets at Liverpool Museum with the help of curatorial staff
from vertebrate and invertebrate zoology, botany and geology departments. Errors (not
shown) are of the order of plus, or minus 20%.
Table 2
Specimen Size Category Codes
Mean Cost/Specimen (Optimally Housed)
Mean
Cost/Specimen Taxonomically Housed
Small
4-10
£0.32
£0.85
Medium
13-16
£0.96
£1.50
Large
1-3, 11-12
£1.78
£3.00
Hence any collection can be split into small, medium and large items and the total
storage cost for a particular specimen will have two components. The physical cost of
requiring space in a cabinet and the personnel cost of time spent handling the specimen,
in order to locate its final resting place in a particular part of a cabinet. The
following example shows how these elements are computed using the Figure 1 data from B39
(Saddleworth Museum).
According to the B39 data 40% (1,074 specimens) of the total 2,685 specimens need to be
adequately housed. From the Collection Profile information these 1,074 specimens can be
split into 900.4 small specimens (84%), 144.8 medium specimens (13%) and 28.8 large
specimens (3%). Using the final column in Table 2 shows that the physical cost of storing
the specimens is:
Small
40% of 2,251 = 900.4 Cost = 900.4 x £0.85 = £ 765
Medium 40% of
3621 = 144.8 Cost = 144.8 x £1.50 = £ 217
Large 40% of 72 = 28.8 Cost = 28.8 x £3.00 = £ 86
............
Physical Storage Cost = £1,068
The personal component of the storage cost is independent of the size of the specimen
and any taxonomic spaces in a storage unit. It is estimated here by assuming that a
Curator G can store 25 items per house. This includes time spent looking up documentation,
locating, physically transporting and re-organising. If it is further assumed that such a
curator earns £4 per hour, then the personnel cost of storage will be 400/25 which comes
to £0.16 per item stored. In the example given for B39 the personnel cost for storing
1,074 specimens is as follows:
Personnel Storage Cost = 1,074 x £0.16 = £ 172
Thus the Total Storage Cost is: £1,068 + £172 = £1,240
If the collection is actively used and hence likely to expand, then the cost of
additional storage units would need to be added to this total.
Documentation Cost
Like 'personnel storage cost', the cost of documenting a collection on computer is
independent of the collection's profile. However data logging is a two-stage process. Not
only must the data for each specimen be typed into the computer, but at a later stage, it
has to be edited for errors and updates. For the purpose of simplicity, both logging and
editing are assumed to take the same amount of time. Thus if an individual can type xx
full data records onto the computer in an hour, then it will take them a further hour to
edit this information.
From personal experience and that of other curators who are heavily involved in this
kind of work, the estimate for xx is 40. Hence 40 complete data records can be logged in
one hour, with a further hour required for checking. This is equivalent to 20 records per
hour and if a Curator G being paid at the rate of £4 per hour is assumed to be doing the
job, then the documentation cost per specimen is: 400p/20 = £0.20.
Referring to the information presented for B39, 90% of this institution's collection has data. For costing documentation it is assumed that (initially anyway) institutions will give priority to data specimens. There is little scientific value in non-data material and although it would at some point be necessary to record the existence of such material, this would not be considered a priority by curators. Hence all non-data specimens have been excluded from the documentation cost (10% for B39). This leaves 90% of 2,685 specimen records (ie 2,416.5). At £0.20 per record documentation would therefore cost:
2416.5 x £0.20 = £483.
Conservation Costs
Table 3 shows the estimated curation cost per specimen and the nature and duration of
some typical conservation tasks for each of the curation categories. A perusal will show
that three basic cost types emerge, which can be defined as Low (Category Codes 4 - 9),
Medium (Category Codes 10 - 16) and High (Category Codes 1 - 3). These figures have been
estimated from the information supplied by curators and conservators at Liverpool Museum
(A59).
It should be pointed out at this stage that estimates of conservation costs per
specimen are much more variable than those for storage. For example, it is possible for
certain specimens in any of the three category groups to need months of intensive
conservation work, costing in effect hundreds of pounds per specimen. However it is
assumed that the majority require little more than cleaning, re-packing, re-pinning,
gluing together...etc. Hence the figures displayed under curation cost represent modal
(most frequently occurring) data. For this reason the error of the estimate is also higher
(typically around 20%).
To produce a conservation estimate, a different collection category pattern is used
from that which formed the basis of the storage cost estimate. It is based on Table 3 and
groups categories according to the Low, Medium and High cost types already outlined.
Table 3
Information on Conservation Costs
Code Conservation Cost per Spec Personnel & Materials Category Conservation Task
Time for a Curator G
01 £8.00 Taxidermy Mounts Remounting, Cleaning, Repair 2 Hours/Sp
02 £6.00 Vertebrate Skins Repacking, Cleaning, Repair 2 Hours/Sp
03 £5.00 Osteological Repacking, Cleaning, Repair 2 Hours/Sp
04 £0.25 Oological Repacking, Cleaning, Repair 0.05 Hours/Sp
05 £0.25 Entomological Repining, Cleaning 0.05 Hours/Sp
06 £0.25 Molluscan Repacking, Cleaning, Repair 0.05 Hours/Sp
07 £0.25 Other Invertebrates (Dried) Repinning, Cleaning 0.05 Hours/Sp
08 £0.25 Spirit Preserved Refilling 0.05 Hours/Sp
09 £0.25 Microscope Slides Repairing, Cleaning 0.05 Hours/Sp
10 £3.00 Herbarium Sheets Cleaning, Remounting, Repair 0.5 Hours/Sp
11 £3.00 Other Botanical (Boxes etc) Cleaning, Repacking, Repair 0.5 Hours/Sp
12 £2.20 Biological Models R epairing, Cleaning 0.5 Hours/Sp
13 £1.60 Rocks Repairing, Cleaning, treating 0.4 Hours/Sp
14 £1.60 Minerals pyrite disease and delamination 0.4 Hours/Sp
15 £1.60 Fossils of fossil bone. Setting up 0.4 Hours/Sp
16 £1.60 Other Geological [controlled environments]. 0.4 Hours/Sp
The B39 data shows that of the 2,685 specimens, 50% require some form of conservation.
This is not to say that 50% of the collection is falling apart! It simply means that half
of the collection needs some (often minimal) amount of intervention to stabilise it and
effectively prevent any possible future deterioration.
Table 4 shows the profile of the 2,685 specimens in the collection.
Table 4
Conservation Type Specimens 50% of Total
Low (Category Code 4-9) 2251 1,126
Medium (Category Code 10-16) 362 181
High (Category Code 1-3) 72 36
Total 2685 1,343
From the 50% of Total column, the half of the collection requiring conservation (n =
1343) is composed of 1,126 specimens at Low Cost conservation, 181 at Medium Cost and 36
at High Cost. Separate estimates for these three components are shown in Table 5.
Table 5
Specimens in each Conservator Costs Conservator plus Materials
Conservation Class Per Specimen Costs per Specimen
Low (1,126) £0.25 £0.50
Medium (181) £2.40 £3.00
High (36) £6.30
Multiplying entries for columns 1 and 3 enables an overall estimate for the cost of conservation to be produced. Hence:
£7.00
1126 x £0.5 = £ 563
181 x £3.0 = £ 543
36 x £7.0 = £ 252
.........
Conservation Cost = £1,358
Thus the overall cost of Storage, Documentation and Conservation (S+D+C), for
Saddleworth Museum, presented in Appendix 1.3 is obtained by summing as follows:
S = £1,240
D = £ 483
C = £1,358
(S+D+C) = £3,081
In concluding, it is important to once again stress the limitations of such statistical
procedures. Although such cost estimates may prove useful, as an aid in shaping policy
guidelines for specific institutions, they should not be viewed as precise parameters, but
merely as direction indicators.
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Created: January 1999; Last updated: 22nd January 1999 by CWP