Thank you Pawan for briefing the LIS community - it is a good attempt I must say. Terms have changed over a period but; utility of print material on shelves was always questioned in the past. "Zero-Growth Principle" is one of the oldest examples of keeping only Updated Knowledge on shelves. with best wishes satish deshpande adroit digital library consultants ----- Original Message ----- From: Pawan Agrawal To: elibrarian ; mlosc ; libtech@yahoogroups.com ; adinetyuva@googlegroups.com ; LIS-Forum ; lislforum@gmail.com Sent: Wednesday, December 29, 2010 5:18 PM Subject: Full explanation: ‘Half-Life’ in the context of library materials. How is it calculated? Dear library Professionals, You must have remember about a question asked in UGC NET exam last Sunday. We were asked a question about half life in context of library material and its calculation. As per the question it's indication was about library material and in that case we can not exclude books half life. I have browsed a lot on this question and received a lot on citation only. cited half life, citing half life, citation half life etc. which was covering only journal or periodicals half life. There was almost nothing on books or other library material. Some how I could get some hints of it and I though I must share it with all of you. I have prepared a short answer of this question which I feel would be useful for you. Half life concept in Bibliometrics Half life is a method though to be practical for evaluating the usefulness of specific library material examines citation half life (for journals) and use half life (for books and other material). Half life studies attempt to evaluate the length of time in which a journal or book is used, either as resources as indicated by citation, or physical use as indicated by circulation (books). Tsay (1998) examines journal or book “life” based on uses as demonstrated by citation or circulation. The premises “half life” in bibliometrics is to determine when half of all the active literature of a field has been published, or the time period that includes half of more of the references made. Short half life, whether citation based or use based which means more than 50% of the use or the citations occurred in a short period of time, implies “new volumes of a title are generally used more often than older volumes”. Half life studies may suggest which library resources are most used, but may also exaggerate use in that there are more publications now than previously. There have been suggestions that half life studies could identify which resources are least used, resulting in a list of items for considered for discontinuation of write off. Caution should be taken in applying such a plan; the mission of the institution, the orientation and the behavior of the users, and any possible other contributors to low use, such as inaccessibility, should be considered. 1995(9 citation or no item issued in a year) 1996 (6) 1997(7) 1998(6) 1999(7) 2000(7) 2001(7) 2002(3) 2003(7) 2004(5) 2005(7) 2006(2) 2007(5) 2008(2) 2009(2) 2010 (1) Half life on the basis of Citation: This can be achieved by subtracting the publication year of the source documents from the median publication year of the documents that cite the source document. We take an example of the data given above. Here, in this example citation data is given for a certain article which was published in 1994. In the table above the account of the citation received by the article from 1995 to 2010 is given. Total number of documents citing this article in period of 16 years is 83. It is also possible that total 83 documents are published during this period on the subject of the article published in 1994. Now If we take out median of the publication date of citing documents it will come 42, which is received in year 2000. Then, 2000 minus 1994 equals six years. So the half life of the article published in 1994 would be of 6 years. Half life on the basis of circulation: This can be achieved by subtracting the acquisition year of the source item from the median of issue years of the document. We can take an example again of the data given above. A resource acquired by a library in the year 1995. The statistics given above are of the circulation in the period of 16 years. Total number of issue of this book in period of 16 year is 83 and the median as similar of the above example comes 42, which is achieved in year 2000. Then, 2000 minus 1995 equals five year. So the half life of the item received in 1995 would be of 5 years. Comments are welcome -- Join hands, Join eLibrarian www.grou.ps/elibrarian Thanks and Regards ------ Pawan R. Agrawal Librarian Takshshila Centre for Learning Transpek Silox Industry Ltd. Kalali Road- Atladra Vadodara- 390012 Ph. 9376135580 http:\\www.grou.ps/elibrarian -- ADINET yuva! You received this message because you are subscribed to the Google Groups "ADINET yuva!" group. To post to this group, send email to adinetyuva@googlegroups.com To unsubscribe from this group, send email to adinetyuva+unsubscribe@googlegroups.com For more options, visit this group at http://groups.google.co.in/group/adinetyuva?hl=en-GB -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.