A study conducted for Hewlett Packard by Delic and Hollmer (2000) where they discuss how much a knowledge based system actually improves Help Desk performance. As been mentioned by various authors it is assumed that Knowledge bases increase performance in Help Desks .  They performed a study over 18 weeks comparing how long Support Analysts took to solve a call using a knowledge base compared not using the knowledge base.  They found that the knowledge base speeded up performance by 10.76 percent.  Which mean that with a knowledge base it took 17.84 minutes overall average using a knowledge base and not using a knowledge base. the average time was brought down to 15.92 minutes using only the knowledge base.  Other studies discussed in the paper was one by the Gartner group which found that a knowledge based system made the speed of the call increase by 22 percent. 

The paper concludes by reiterating what other authors have found that knowledge based systems have more of an impact than just call resolutions but they impact on the overall learning of the organisation and personnel training.

However knowledge technologies are not suited to all Help Desk environments they are at their most effective when used in large customer support environments where they calls are of repetitive nature.  The use of Expert system is not advised where the information is changing week to week.  Barr (1990) advises that Case Based reasoning tools approach is better where information is changing regularly.  Purchasing these tools can be expensive plus there is the effort involved in engineering the knowledge can take a lot of resources.  They are most commonly used in first line support for providing answers to simple queries.  The Support Analysts using the knowledge base does no have to expensive skilled programmers and technicians.  These types of knowledge have been implemented successfully in such things like large PC support environments.  They are less effective in second and third line support where they are mainly configuration problems and high levels of skills are needed.