PSM

Problem Solving Methodology

PSM OverviewAnalysis Design Development Evaluation

Solution Requirements

Solution Constraints

Solution Scope

Solution Design

Manipulation (Coding) Strategy

Evaluation Criteria Validation

Testing

Reporting

Documentation

Analysis Stage - Overview

• Analysis typically answers the 'what questions'

– What will solve a problem, given particular circumstances?

– What benefits will the solution bring to the user?

Analysis

Solution Requirements

Solution Constraints

Solution Scope

Analysis Stage - Tools

• Tools to assist in determining the solution requirements include – context diagrams (level 0 DFD)– data flow diagrams and – use case diagrams

Analysis Stage – Requirements• Determining the solution requirements.

– What information does the solution have to provide? – What data is needed to produce the information? – What functions does the solution have to provide?

• These requirements can be classified as being: – functional, namely what the solution is required to do, and – non-functional, which describes the attributes the solution should

possess, such as • user-friendliness, • reliability, • portability, • robustness, • maintainability.

Analysis Stage - Constraints

• Identifying the constraints on the solution.– What conditions need to be considered when designing a

solution? – Typical constraints include

• cost,• speed of processing, • requirements of users, • legal requirements, • security, • compatibility, • level of expertise, • capacity, • availability of equipment.

Analysis Stage - Scope

• Determining the scope of the solution. – What can the solution do? – What can't the solution do? – What are the benefits of the solution to the user? – The scope states the boundaries or parameters of

the solution. Benefits can be stated in terms of their efficiency and effectiveness.

Design Stage - Overview

• Planning how the solution will function

• The appearance of the resulting information.

• The solution design typically involves identifying:– What specific data is required– How the data will be named,

structured, validated and manipulated.• Evaluation Criteria

Design

Solution Design

Evaluation Criteria

Design Stage – Design Tools

• Typical design tools for this purpose include – data dictionaries and data structure diagrams, – input-process-output (IPO) charts,– flowcharts, – Pseudo-code– Object descriptions.

Development Stage - Overview

• Electronically manipulating (or coding) data to 'build' or create the solution following initial designs.

• Validation and Testing• Where appropriate, internal

documentation is also written, which documents the functioning of the solution.

• Writing documentation to support the use of the solution.

Development

Manipulation (Coding)

Validation

Testing

Documentation

Development Stage - Validation

• Validation to check for the reasonableness of data being input.

• Validation can be both manual and electronic. – Proofreading is a manual technique and it occurs

when data is entered directly into the solution and remains fixed, such as in a web page.

– When the validation process has been built into the solution (electronic technique), then its effectiveness is determined through the testing activity.

Development Stage - Testing

• Testing whether the solution does what it was intended to do. This activity typically involves: – establishing what tests will be conducted– determining what test data, if any, will be used– determining expected results– conducting the test– recording the actual results– correcting any identified errors.

Development Stage - Documentation

• Will involve both internal and external documentation– Internal is use to help other programmers

understand your code– External documents are intended for the user

typically in the form of USER MANUALS.

Evaluation Stage

• Strategy involved to effectively evaluate the solution/product

• Reporting on how the well the solution met all requirements of the user.

Evaluation

Strategy

Reporting

Evaluation Stage – Strategy

• Determining a strategy for finding out the extent to which the solution meets the required needs. Typically this would include – Specifying a timeline– Outlining what data will be collected and by what

methods and techniques, and – How the data relates to the criteria, which were

developed in the designing stage.– More than just asking user a list of questions…

Evaluation Stage – Reporting

• Reporting on the extent to which the solution meets the requirements of the user. – It usually takes place after the solution has been

used by the user/client and is based on the criteria developed in the designing stage.

Scope

• How much should the solution be able to achieve?

• The scope of a project defines:– How big it is going to be.– How broadly it will search for causes and possible

solutions to the problem.– What should the solution be able do? – What limitations are acceptable in the solution? – What should be the benefits of the solution to the

user?

ScopeThe scope states the boundaries or parameters of the solution in terms of their

efficiency and effectiveness.Will it be a Narrow Scope? A Broad Scope?

• More tightly limits the changes required.

• to be smaller and quicker to finish.

• It makes more assumptions about the true cause and best solution of the problem.

• Wrong assumptions can prevent solving of problem (thus terminates)

• Entails a lot of changes and lots of work

• Project tend to be bigger and slower.• Requires more investigation of different

factors before deciding on a solution. • Will affect more parts of the information

system. • Makes fewer assumptions about the

cause and solution of a problem.

• More likely to accurately identify the true cause of a problem and fix the problem effectively.

Scope - Example

• The requirement is a faster internet connection is needed.– one could simply increase bandwidth (a narrow

scope, because it assumes inadequate bandwidth is the cause of the problem)

– one could investigate all of one's internet hardware and software (a broad scope) before designing a solution.

Constraints