Broad Strategies for identifying System Requirements (Davis, 1982)

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1 Broad Strategies for identifying System Requirements (Davis, 1982) e basic strategies… …ask users … derive from an existing system … derive from a ‘formal’ analytical procedure or model … derive by experimentation and evolu Users : r a stable system with a well-understo ture (e.g. typical admin-type applicat K if excessive anchoring excessive concreteness excessive recency d limit users’ vision of the new syste

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Broad Strategies for identifying System Requirements (Davis, 1982). The basic strategies… …ask users … derive from an existing system … derive from a ‘formal’ analytical procedure or model … derive by experimentation and evolution. Ask Users : - PowerPoint PPT Presentation

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Page 1: Broad Strategies for identifying  System Requirements (Davis, 1982)

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Broad Strategies for identifying System Requirements (Davis, 1982)

The basic strategies… …ask users … derive from an existing system … derive from a ‘formal’ analytical procedure or model … derive by experimentation and evolution

Ask Users : OK for a stable system with a well-understoodstructure (e.g. typical admin-type applications)

Not OK if …excessive anchoring …excessive concreteness … excessive recency could limit users’ vision of the new system

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Excessive Anchoring?An inability to see how things might be different from the present.

Excessive Concreteness?An inability to take an abstract view.

Excessive Recency?Being over-influenced by recent problems orevents.

Derive from an existing system in same or different organisation : OK where there are satisfactory precedents.But anchoring remains a danger.

Derive from a ‘formal’ analyticalprocedure or model :Use when major change is needed and anchoring/recency/concreteness could be a problem Use as a check on first two strategies.

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Some examples of ‘formal’ procedures/models

...Critical Success Factor Analysis (CSF)

… Business process/data modelling and redesign (e.g. ERP, BPR, SSADM)

…Decision Analysis (identify key decisions develop algorithms identify information needs)

… Normative models like BIAIT

“Bill or accept cash?”“Immediate or future delivery?”“Need to keep history of customers’ purchases?”“Rent or sell?”“Make to order or to stock?”“Fixed or negotiated prices?”

… Strategy Set Transformation

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Discover requirements by experimentation and evolution :Use when no exemplar exists and no model or ‘formal’ procedure can be guaranteed to deliver the goods and/or where needs are changing.

Davis’s big point...

Low

High

Ask users

Derive from an existing system

Derive from an analytical procedure/model

Derive by experimentation / evolution

Uncertainty about what’s needed...

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What factors contribute to uncertaintyabout what’s needed?•Bad organisational factors e.g. nasty politics, unclear roles, dissagreement, diverse users

•Very complexapplication

•Inexperienced users

•Inexperienced analysts

•etc…...

Examples...

Insurance company reserving system.Standard costing system for bakery.

Reference :“Strategies for Information Requirements Determination”G.B. Davis, IBM Systems Journal, Vol.21(1), 1982, pp.4-30.