Literature of a subject grows exponentially with time. The practical librarians, who administer growing collections in finite spaces, look to research on obsolescence to help them decide which items to keep and which to store or discard in order to make room for the new acquisitions. Obsolescence has been defined by Line and Sandison as the “decline over time in validity or utility of information.” This concept is of obvious interest to information theoreticians who concern themselves with the development, career and eventual death or incorporation of particular kinds of information. A measure of the obsolescence rate of literature, which can be assessed by citation analysis, can give an indication of how far a search must go back to obtain a representative sample of the published literature in a given field. Perhaps the most famous recent study of obsolescence has been the Kent’s study at the University of Pittsburgh. The purpose of the study was to develop measures for determining the extent to which library materials are used and what the costs are, to improve acquisition decisions, and to determine storage or discarding points at which alternatives to local ownership of various items became feasible.

The present study was conceived to study the characteristics of literature of political science, by determining half-life and certain other factors related to obsolescence, applying citation analysis techniques. The objectives of the study are to determine the following factors: - Annual Aging Factor (AAF) - Half – Life (h) - Mean – Life (m) - Utility Factor (u) - The Corrected Obsolescence (α) Factor in different disciplines of Social Science.

The following tables show the citation frequency in the subject concerned. 2

Tables 4.1 & 4.2 indicates citation frequency for Political Science in Kurukshetra University

1. References as old as 100 years have been cited. 2. It may be observed that while books published 100 years ago have been cited, the periodicals cited go to the extent of 56 years. 3. While 70 % of the periodicals are within 34 years of age, the corresponding figure for books is 51 years. 4. It is interesting to note that 50% of periodical citations are within 21 years and books within 35 years. The above findings reveal that in Political Science old literature is very important. The data of column 3 of Table 4.3 are plotted as frequency polygon ‘AA’ in figure 4.3. The curve ‘AA’ looks like a negative exponential distribution. The data indicate roughly while an initial build up occurs from the first entry.

0.004.008.0012.0016.0020.001.00 10.00 100.00 1000.00 10000.00

0.10 0.30 0.50 0.70 0.90

0.20 0.40 0.60 0.80 1.00 20.0024.0028.0032.0036.0040.0040.0044.0048.0052.0056.00

0.004.008.0012.0016.0020.00 1.00 10.00 100.00 1000.00 10000.00

0.10 0.30 0.50 0.70 0.90

0.20 0.40 0.60 0.80 1.00 20.0024.0028.0032.0036.0040.0040.0044.0048.0052.0056.0060.0060.0064.0068.0072.0076.0080.0080.0084.0088.0092.0096.00100.00

4

0

0.5

1

1.5

2

2.5

3

3.5

4

13579111315171921232527293133353739414345474951535557

Series2

Figure 9.9 Figure 4.3

The graphical method suggested by Brookes has been followed to compute the Annual Aging Factor (a) and further on the basis of ‘a’ the various obsolescence factors have been calculated. The data of column 6 of Tables 41 to 4.3 were plotted separately on a semi logarithmic graph paper taking cumulative frequencies of citations T(t) on Y-axis and the age of citations in years (t) on X-axis ( Figures 4.1-4.2) XY, X1Y1 and X2Y2 represent on the semi logarithmic graph, for t=0 to 20; t-20 to 40; t=40 to 60 respectively T(t) is the citations in Tail that is the cumulative frequency of citations cited to tth year. The straight line ‘OA’ is drawn parallel to the XY at the point T (t) = 10,000. On this line T (t) for t = 1 gives the value of t (1) = a1 = a, the Annual Aging Factor. The scale on the left hand side is graduated to find out the different values of ‘a’ directly from the graphs from 1.0 to 0.001. The straight line ‘OA’ directly forms the graphs from 1.0 to 0.001. The straight line ‘OA’ reads the values ‘t’ = 0 to t=20 and the value for ‘a’ on the line of the extreme right is taken to the left hand side, another line 01A1 is drawn parallel to XY or OA to read the values for t=20 to t=40.

The Annual Aging Factor has been calculated using the following formula: T (t) = at The value of a, using OA and A1O1 was identified and the average values of ‘a’ was calculated and the same is given in Table 4.3. The average value of Annual Aging Factor of literature cited in Political Science Journals can be taken as 0.9755. From this, it may be inferred that AAF of cited journals and books in different subjects of social sciences varies in Kurukshetra University. The reasons for this

Half-life is the period of time during which a half of the currently cited literature was published. The half-life can be determined from the graph such that the relation ah = 0.5 will hold good. a h = 0.5 The Half-Life of literature cited as calculated from the above relation. The Half-Life of books is high when compared to journal articles.

The Mean (m) of the distribution can be obtained from Annual Aging Factor (a) using the following relationship; m = loge 1/a The Mean-Life of cited journal articles and books show variation (Table 4.3).

The utility factor (u) has been calculated using the relationship. This relationship shows that the Utility Factor will be high only when the AAF is high. It is observed that the lowest Utility Factor was found in journals and followed in increasing order in books.

The Obsolescence Factor (α) has been computed using the following formula: Accordingly, Corrected Obsolescence Factor (α) was determined is given in Table 4.3. It is observed that the Corrected Obsolescence Factor also found to be varying in both case of cited journals articles and books.

It is indicated from the above tables that the Research Scholars in Political Science have cited old documents. It will be useful to find out the nature of distribution of cited documents over a period to ascertain any definite relation among subjects. For this purposes graph of number of citations versus age of cited documents were developed individually (Figure 4.3).It is observed that the decay curve consists of two distinct portions, one corresponding to recent literature and the other to the older. The graphs show that the points are concentrated at one end, and the curve gradually tapers off to zero at the other end. Hence, it may be said that the pattern of distribution of citation follows a negative exponential distribution (Figure 4.3).

The librarian is faced with the problem of deciding on the matter of the optimum size of the document collection and back runs of the same, of ascertaining the utility of old volumes and old editions etc. There is no direct measure available to him, which would give him a clear cutoff value in terms of age of the documents. Generally, in a University Library, it would be easier to calculate the rate of obsolescence and derive a policy by which it would be possible to discard the old volumes of the same age. This technique, however, does not take into account the fact that some journals are more useful than the others are. This method would lead to a faulty weeding policy, and hence not the best solution to the problems. From the present study, it is noted that one cannot generalize the weeding policy; however, the decision should be taken by considering the subjects individually. Literature as old as 100 years in Political Science has been cited. Hence, after the respective period of a particular subject the documents may be weeded out or may be sent to the dormitory section. From the above discussion, it can be concluded that the obsolescence factors such as annual aging, half-life, mean-life; utility factor for the cited journal literature and books varies in social sciences and the values are very high when compared to various implications in the formulation of policies relating to the planning, organization and weeding of materials, bindings of books and journals; retrospective searching of literature etc. in libraries.

1. LINE (Maurice B) and SANDISON (Alexander). Obsolescence and changes in the use of literature with time. Journal of Documentation. 30, 3; 1974; 283-350. 2. BROOKES (B C). Growth, utility and obsolescence of scientific periodical literature. Journal of Documentation. 26, 4; 1970; 283-294. 3. GUPTA (Davendra K) and GUPTA (Sushma). Periodical literature of Petroleum geology: A citation analysis study to determine obsolescence factors and patterns. IASLIC Bulletin. 28, 2; 1983; 75-86. 4. BURTON (R E) and KEBLER (R W). Half-Life of some scientific and technical literature. American Documentation. 11, 1; 1960; 18-22. 5. GRIFFITH (Belver C) and others. The aging of scientific literature: A citation analysis. Journal of Documentation. 35, 3; 1979; 179-196.