A second way of measuring the actual collection is qualitative. These measure the quality of the materials within the collection, as well as the raw numbers. There are four techniques that can be used to measure the quality of the collection.
Appearance shelf-scanning. This is a quick method of evaluation in which the library staff simply looks at the appearance of the collection within a specific section. Books that look old and dilapidated are not likely to be attractive to readers. If materials within the section are not attractive, a weeding program may be established before further assessment.
Date of materials. Another method is to look at the publication dates of the materials within a section of the collection. In many subject areas, particularly in the natural sciences, technology and social sciences, information is very date-sensitive. Information on computers that is more than a couple of years old, for example, is usually obsolete. To measure the currency of information within a subject area, one method is simply to look at the mean and median ages of the materials.
If you have an automated system, it may be possible for the system to give you this information. If the system will not do this, or if you are working with a manual system, you can determine these figures by simply listing the publication dates of all materials (or a random sample of materials if you have a very large collection). To find the mean age, you simply add all of the publication dates together and divide by the total number of items. For example, if you have ten books whose publication dates are: 1967, 1970, 1978, 1980, 1990, 1990, 1996, 1997, 1998 and 1999. The total of these numbers is 19,865, which, when divided by 10, equals 1986.5. In 2000, this means that the average book in the collection is about 13 years old.
A look at the median gives a little different story. The median is the midpoint in the range of dates. In this case the midpoint is 1990, since half the books have dates that are older than 1990 and half are newer than 1990. This means that half the books in the section have been purchased in the last ten years.
The mean and median age of the materials is then compared to a standard that the library has set before doing the assessment. For example, if the books in the above example are in a history section, the collection may be considered perfectly up-to-date, as the older materials may not have been significantly dated by newer research. For a section on medicine or computers, however, the age of these materials may be a signal to look more closely at the currency of your collection.
Comparisons with standardized lists. Standardized lists are lists of materials that are recommended by subject experts. The best-known of these lists are the H.W. Wilson catalogs. These include The Children's Catalog (fiction and non-fiction for elementary school age children), The Middle and Junior High School Catalog (fiction and non-fiction), The Senior High School Catalog (fiction and non-fiction), The Public Library Catalog (adult non-fiction), and The Fiction Catalog (adult fiction). These lists tend to be somewhat dated, but can be updated using annual lists of recommendations from periodicals such as Booklist, Library Journal and School Library Journal.
In this method, the titles in the section are examined to see if they were recommended in the standardized lists, or if the library collection is large, the percentage of materials recommended by the list that is held within the collection. It is generally assumed that the collection is of higher quality if it contains more recommended materials. Because this method is quite time consuming, it is generally not used unless a specific problem with a section has been identified and it is assumed that the section must be improved.
Expert opinion. In some cases the library may seek help in evaluating its collection from outside experts. For example, a public library may ask a garden club to evaluate its gardening section. In schools it can be appropriate to ask the various academic departments to evaluate the sections that support their curriculum.
When using outside experts, it is important to carefully explain the limitations of the library's collection development policy and budget. Experts should not be given the impression that whatever changes they recommend will automatically occur.
Click on the arrow to go on to next page