Showing posts with label Production planning and control. Show all posts
Showing posts with label Production planning and control. Show all posts

April 16, 2015

Organizational Sociology

Organizations emerged as a recognized field of social scientific study during the 1950s.


The two academic centers most critical in shaping this nascent discipline were the Carnegie Institute of Technology (now Carnegie-Mellon University) and Columbia University. The Carnegie group included political scientists, economists, and psychologists. Collaborative work of March & Simon 1958 analysed organization.

The Columbia scholars, under the leadership of Merton, were all sociologists.  Simon and colleagues at Carnegie worked from a model—that of “bounded rationality”—that neatly linked arguments stressing purpose and intentionality with the recognition of cognitive and social constraints restricting such rational action (Simon 1945, March & Simon 1958, Cyert & March 1963).

Merton (1949) at Columbia emphasized the “unintended consequences of purposive action,” and his junior colleagues, who carried out early definitive studies of public and private organizations, each gave his own twist to the enquiry. Blau (1955) focused on the “dilemmas” of bureaucracy, as formal structures designed to solve one problem give rise to others; and Gouldner (1954) wrote of the “Janus-faced” nature of organizations as systems of coercion and consent.

In the United Kingdom, an eclectic collection of organizational scholars pursued a “socio-technical” model, insisting that organizations represented a “coupling of dissimilars” (Emery 1959).


http://www.annualreviews.org/doi/full/10.1146/annurev.soc.30.012703.110644

http://workinprogress.oowsection.org/2014/10/29/panel-the-future-of-organizational-sociology/

November 25, 2011

Safety Stock Determination

In Economic Order Quantity (EOQ) systems, safety stocks are to be kept and they have to be specified to calculate the reorder point. Safety stocks are kept to minimize the chances of stock out. If the average lead time of past receipts and average lead time consumption of the last year are used to calculate the reorder point, in 50% of the reorders, stock outs can take place.

One of the methods of determining safety stock to reduce the probability of stock out,  is to assume that lead time will not vary, but the demand varies. The standard deviation of demand can be determined and a safety factor can be used based on normal distribution tables.

If safety stock is kept equal to one standard deviation of demand during lead time the service level (probability of stock being available during the time the item is on order) will go up to 84.13%. If the safety stock is made equal to two standard deviations of demand during lead time the service level (probability of stock being available during the time the item is on order) will go up to 97.72%.

Plossl and Wight advocate using mean absolute deviation (MAD) in the place of standard deviation. The standard deviation can be approximated as 1.25 times MAD.


Recent articles and research papers on the topic

Safety stock analysis: A tutorial
http://scm.ncsu.edu/scm-articles/article/safety-stock-analysis-inventory-management-models-a-tutorial

A new framework for safety stock management - Cognizant insight note December 2011
http://www.cognizant.com/InsightsWhitepapers/A-New-Framework-for-Safety-Stock-Management.pdf

Concepts for Safety Stock Determination under Stochastic Demand and Different types random production yield, February 2011
Working Paper, University of Magdeburg
http://www.fww.ovgu.de/fww_media/femm/femm_2011/2011_03.pdf


Originally posted on Knol: http://knol.google.com/k/narayana-rao/safety-stock-determination/2utb2lsm2k7a/ 594#