1 Chapter 14 The Systems Development Process, Part II: System Selection, Detailed Design, and System Implementation.

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Chapter 14

The Systems Development Process, Part II: System Selection, Detailed Design, and System Implementation

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Objectives for Chapter 14 Factors to be considered in a detailed feasibility study The three major steps involved in a cost-benefit analysis of proposed

information systems Advantages and disadvantages of the commercial software option,

and the decision-making process used to select commercial software The sequence of events that constitute the detailed design phase of

the SDLC The design procedure for both hard-copy and electronic input and

output media The design of the process component of a system Principal features of a system implementation, including the use of

PERT and GANTT charts to create an implementation schedule The different types of system documentation and the purposes they

serve Procedures employed in database and system conversion

The Seven Stages of the SDLC

SystemsPlanning

SystemsAnalysis

ConceptualDesign

SystemSelection

DetailedDesign

SystemImplementation

Maintenance

New Systems Development

SYSTEMS DEVELOPMENT LIFE CYCLE

ProjectProposals &Schedules

SystemsAnalysisReport

MultipleConceptualDesigns

SystemSelectionReport

DetailedSystemDesign

FullyDocumentedSystem

Required Documentation

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Stage 4: System Evaluation and Selection

This phase is an optimization process that seeks to identify the best system and make an informed decision under uncertain circumstances.

Two steps detailed feasibility study cost-benefit analysis

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Detailed Feasibility StudyThis should be performed by an

informed, but independent group: the project manager user representatives systems professionals who are not a

part of the project

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Feasibility Factors

Technical - well-established and understood technologies represent less risk and will receive a higher score

Legal - need to assess critical control, security, audit trail, and privacy issues

Operational - the availability of well-trained, motivated, and experienced users must be assessed

Schedule - need to assess available development tools, the technology platform, the systems design, and user training requirements

Economic - costs are becoming better defined and assessment becomes easier

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Cost-Benefit Analysis

Cost-benefit analysis helps management determine whether the benefits received from a proposed system will outweigh its costs.

It is useful for comparing competing systems designs.

Intangible benefits make this process difficult.

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Cost-Benefit AnalysisIdentify the costs.Identify the benefits.Compare the two.

Period1 2 3 4 5 6 7

$

500

400

300

200

100 0

Present Value of Total Costs

Present Value of T

otal Benefits

Pa

yba

ck P

oin

t

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Identification of Costs and Benefits

Examples of One-Time Costs: hardware and software acquisition training personnel

Examples of Recurring Costs: hardware and software maintenance personnel

Examples of Tangible Benefits: increased sales within existing markets labor reduction

Examples of Intangible Benefits: increased customer satisfaction improved employee satisfaction

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Systems Selection Report

This formal document consists of a: revised feasibility study cost-benefit analysis list and explanation of

intangible benefits for each alternative

On the basis of this report, the steering committee will select a single system.

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The Purchase of Commercial Systems Packages

Four factors have stimulated the growth of commercial software: relatively low cost prevalence of industry-specific

vendors growing demand by small businesses trend toward downsizing and

distributed data processing

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Types of Commercial Systems Packages

Turnkey systems are completely finished and tested systems that are ready for implementation.

Backbone systems provide a basic system structure on which to build.

Vendor-supported systems are custom-developed and maintained by a vendor for a customer.

ERP systems are difficult to classify since they have characteristics of all of the above.

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Pros and Cons of Commercial Software

Advantages: decreased implementation time decreased cost reduced probability of program errors

Disadvantages: reduced independence - the customer is

dependent on the vendor for maintenance less flexibility in system greater difficulty in modifying the system as

needs change over time

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Four Steps in Choosing a Commercial Package

Analyze needs and develop detailed specifications of the system requirements.

Send out the Request for Proposals to all prospective vendors to serve as a comparative basis for initial screening.

Gather the facts about each vendor’s system using multiple sources and techniques.

Analyze the findings and make a final selection.

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The Role of Accountants in Evaluation and Selection

The accountant should ensure that: only escapable costs are used in

calculations of cost savings benefits reasonable interest rates are used in

measuring present values of cash flows one-time and recurring costs are

completely and accurately reported realistic useful lives are used in

comparing competing projects intangible benefits are assigned

reasonable financial values

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Stage 5: Detailed Systems Design

This stage follows a logical sequence of events: data model the business process and

design conceptual views design the normalized database

tables design the physical user views (output

and input views) develop the process modules specify the system controls perform a system walkthrough

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Data Modeling

Data Modeling is the task of formalizing the data requirements of the business process as a conceptual model.

The primary tool is the ER diagram which is used to depict the entities or data objects in the system.

Each entity in an ER diagram is a candidate for a conceptual user view that must be supported by the database.

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The Normalization Process

A process which systematically splits unnormalized complex tables into smaller tables that meet two conditions: all nonkey (secondary) attributes in the

table are dependent on the primary key all nonkey attributes are independent of the

other nonkey attributesWhen unnormalized tables are split and

reduced to third normal form, they must then be linked together by foreign keys.

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Designing Output ViewsOutput is the information produced by the

system to support user tasks and decisions.Output attributes:

relevant summarization except orientation timely accurate complete concise

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Output Reporting Techniques

Different users prefer different styles of output (tables, matrices, charts, and graphs) and modes of output (hard copy vs. display screen).

Systems designers must identify these styles and provide output in the desired style.

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Designing Input Views

Data input views are used to capture the relevant facts about the resources, events, and agents involved in business process transactions.

Input may be either hard copy input documents or electronic input.

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Designing Hard Copy Input

Items to Consider: How will the document be handled?

What quality paper? How long will the form be stored and in

what type of environment? How many copies are required? What size form is necessary? Non-

standard form can cause printing and storage problems.

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Hard Copy Form Design

The objective is to design the form so as to reduce clerical errors and omissions and allow the data to be collected as efficiently as possible.

Zones- areas that contain related data-use lines, captions, or boxes

Embedded instructions - should be on the form, not as a separate sheet, and should be written in an active voice

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User’s View - Purchase Order

Purchase Order PO 39763

Vendor NameVendor Address

Telephone:OrderDate

DateRequired

VendorNumber

Terms

PartNo.

Description Qty Unit Price ExtendedPrice

Total Cost

1

2

3 4

56

7 8

9 10 11 12

13

9

9

9 10

10

10

11

11

11

12

12

12 Cal

cula

ted

Fie

ld

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Designing Electronic Input

Input may be from either a source document or data found directly in the computer system.

SourceDocument

SourceDocument

ElectronicInput

ElectronicInput

DataCollection

EconomicEvent

EconomicEvent

TransactionFile

TransactionFile

File

Audit Trail

Input From SourceDocument

Direct Input

Audit Trail

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Direct Input

This method can reduce the input errors that result from additional clerical steps involved in input from source documents.

Direct data collection uses intelligent forms for online editing that help the user complete the forms and make calculations automatically.

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Data Entry Devices

point-of-sale terminalstouch screensmousemagnetic ink character

recognition devicesoptical character recognition devicesvoice and touch-tone recognition

devices

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Designing the Process Component

This phase begins with the DFDs produced in the general design phase.

The first task is to decompose the existing DFDs to a degree of detail that will serve as the basis for creating structure diagrams.

The structure diagrams will provide the blueprints for writing the actual program modules.

Lower-Level DFD for an AP Process

1.1 1.31.2

1.4.1 1.4.3 1.4.41.4.2

AuthorizePurchase

1.4.6

1.4.71.4.5

1.5

OrderGoods

ReceiveGoods

Vendor

ReceiveP.R.

ReceiveP.O.

ReceiveRec. Rpt.

ReceiveInvoice

PRFile

Open POFile

RRFile

InvoiceFile

PreparePayment

Review &Compare Prepare

Voucher

Update AP & PrepareVoucher

AP Sub-Ledger

VoucherRegister General

LedgerDepartment

PurchaseReq

PurchaseOrder

ReceivingReport

Invoice

PaymentVoucher

ApprovedLiabilities

PostPostingData

Journal Voucher

Post

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The Modular Approach

Each module performs a single task.

Correctly designed modules possess two attributes: loosely coupled (low amounts of

exchange of data between modules) strongly cohesive (small number of

tasks performed in each module)

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Pseudocode

Allows the functional characteristics and logic of the modules to be expressed without having to code in any specific programming language

Allows end users to be actively involved in this step even though they may lack programming skills

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Design System Controls

The last step in the detailed design phase. Need to consider: computer processing controls database controls manual controls over input to and output from

the system operational environment controls

This step allows the design team to review, modify, and evaluate controls with a system-wide perspective that did not exist when each module was being designed independently.

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System Design Walkthrough

This step is performed by the development team to ensure the design is free from conceptual errors that could become programmed into the final system.

Some firms may use a quality assurance group to perform the task. This is an independent group of programmers, analysts, users, and internal auditors.

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Stage 6: Systems Implementation

The steps that have the greatest impact on accountants and auditors are: managing the systems implementation developing system software documenting the system software converting the databases converting to the new system conducting the post-implementation review

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Managing the Systems Implementation

An implementation schedule must be created. Project Evaluation and Review

Techniques (PERT) Charts - show the relationships among the many activities. The critical path shows which activities, if delayed, can cause the overall project to be delayed.

GANTT Charts - a horizontal bar chart which shows the project time frame at a glance and compares budget with actual implementation times.

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Developing Application Software

If the organization intends to develop software in-house, then a programming language must be selected.

Programming Languages

Generation Language Example1GL Machine 010110000010000000010000001110

000110000110000000100000111000110101100000100011000100000011

2GL Assembly(symbolic)

L 2,AA 2,BST 2,C

3GL High-level(compiler)

ADD SALARY, COMMISSION,GIVING TOTAL PAY

4GL Natural COMPUTE TOTAL PAY OF ALLEMPLOYEES BY ADDING THEIRSALARY AND COMMISSION

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3rd Generation LanguagesCOBOL, FORTRAN, C, BASIC, and PL1,

among others3GLs function efficiently because

they are compiled programs.The operational procedures are

specified in precise detail which allows greater control over process functionality.

The code is clearly visible to the programmers, which facilitates debugging and maintenance.

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4th Generation Languages

Program generators, query languages, and screen and report generators

The designer may more easily experiment and design as they go.

These languages are easier for non-technical staff to use.

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The Modular Approach to Programming

Promotes programming efficiency since modules can be both programmed and tested independently

Promotes maintenance efficiency since small modules are easier to analyze and change

Promotes greater control since they are less likely to contain material errors of fraudulent logic

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Software Testing

Programs must be thoroughly tested before they are implemented.

Individual modules should be tested with test data containing both “good” and “bad” data. All logic procedures should be tested.

After the individual modules have been tested, the entire system should be tested as a whole.

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Documenting the System

Documentation describes how the system works and should be made for: designers and programmers - comment

lines in programs, system flowcharts, and program flowcharts

operator documentation - run manuals user documentation - instructions on how

to use the system, tutorials, and help features

accountants and auditors - all of the above as well as document flowcharts

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Converting the DatabasesThis is the transfer of data from its current form to

the format or medium required by the new system.Data conversion is risky and must be carefully

controlled by the following precautions: validation - old database must be inspected

before conversion reconciliation - after the conversion, the new

database must be reconciled against the original backup - copies of the original files must be

kept as backup against discrepancies in the converted data

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Converting to the New System

Three approaches:Cold turkey cutover (plunge) - the firm

switches to the new system on a particular day and simultaneously terminates the old system. This is the riskiest approach.

Phased cutover - modules are implemented in a piecemeal fashion. The risk of a devastating failure can be reduced.

Parallel cutover - the old system and new system are run simultaneously. This is the safest, yet costliest, approach.

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Post-Implementation Review

The objective is to measure the success of the system and of the process after the dust has settled. Want to assess: system design adequacy accuracy of time, cost, and benefit

estimatesThis information can provide

feedback to improve future systems development projects.

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The Role of Accountants

Most system failures are due to poor designs and improper implementation. Accountants should provide their expertise to help avoid inadequate systems by: providing technical expertise for

financial reporting requirements specifying documentation standards for

auditing purposes verifying control adequacy in accordance

with SAS 78