COMPLEXITY INDEX FOR A DESIGN ACTIVITY

SANJEEV SINHAPhD Student

Supervisors:•DR. A. I. THOMSON

(DMEM)

• DR. B. KUMAR

(CIVIL ENGG.)

UNIVERSITY OF STRATHCLYDE, GLASGOW, SCOTLAND

RESEARCH OBJECTIVES

• DEVELOP A MODEL FOR MEASURING THE COMPLEXITY OF A DESIGN ACTIVITY

• IMPLEMENTATION OF THE MODEL

• VALIDATING THE MODEL USING CASE STUDIES

• CHECK OVERRUNS IN COST AND SCHEDULE OF DESIGN PROJECTS

• COMPLEXITY AS ONE OF THE TOOLS FOR DETERMINING MANAGERIAL ACTIONS

• APPROPRIATE PRACTICAL ACCEPTANCE IN MANAGING PROJECTS

NEED FOR MEASURING COMPLEXITY IN DESIGN CONTEXT

IMPORTANCE OF MEASUREMENT

“ When you can measure ----------- you know something about it; but when you cannot -------- your knowledge is of meagre and unsatisfactory kind

- Lord Kelvin

‘You Cannot Control What You Cannot Measure’

- Tom De Marco

CHANGING MARKET SCENARIO

A CASE OF CONSTANT MOVING TARGET

YEARS

TIM

E T

O M

AR

KE

T

>5 YEARS

4-5 YEARS

3-4 YEARS2-3 YEARS

VERY SIMPLE

SIMPLE

COMPLEX

VERY COMPLEX

TIME TO MARKET

PRODUCT COMPLEXITY

DECREASED TIME TO MARKET

INCREASED LEVEL OF COMPLEXITY

PRASAD BIREN,1998

PRELIMINARY INVESTIGATIONS

DEFINITION OF COMPLEXITY

• Dynamic

• Relative

• Subjective

• Context Dependent

DESIGN COMPLEXITY AND ITS COMPLEXITY GENERATING FACTORS (CGFs)

DESIGN COMPLEXITY

WORK TIME

MOTIVATIONAL SOCIAL

Usage of Resources

Familiarity with the tasks

Geographical Locations

Competition for Resources

Individual preference

Company’s reputation

Availability of Resources

Proximity of departments

Length of the project

Access to Resources

Cultures involved

Relationships among the workers

ETC.

ETC.

ETC.

ETC.

PROPOSED MODEL FOR MEASURING COMPLEXITY OF A DESIGN ACTIVITY

User Design Activity

CGFs Pcgf

Part of a context

Pcgfs

PCIInformation Parameters

(IP)

Type of Design Activities

OCIInformation

Content of the selected Pcgf

                      PCI is Partial Complexity Index

OCI is Overall Complexity Index

Contextual Module

Partial CGFs Module

Information Proceesing

Example: Manufacture of a pencil

E F Wood Barrel G

Components of a pencil

E: Eraser

F: Ferrule

G: Graphite

Design Activities pertaining to:

•Eraser: cut to length

•Ferrule: blank, roll, stake

•Wooden Barrel: saw, mill

•Pencil:- assemble, paint, print, sharpen

•Package-box, label,carton

Problem Statement

To measure the Complexity Index of machining activity involved in the manufacture of a pencil.

Design activities involved are-

• Machining

• Assembling

• Painting and packaging

PROPOSED MODEL

Assumptions

• Human resources are skilled

• Time associated with the different states of information parameters (IPs) has been set after taking into consideration the average skills needed by a machine operator to do that activity

• Demand of the component is known

M N

I=1 J=1

    

  

Information Content = - Σ Σ pij log2 pij

M= number of skills used

N= number of Information Parameters (IPs) at skill j

pij = probability of using the IP in state i

COMPLEXITY MEASUREMENT:Function of information content associated with its Complexity Generating Factors(CGFs)

CALCULATIONSSub-Process Used: Machining

Skill used : Basic Machining Operations

Information parameters (IPs): Cutting, Milling

Different States of IPs: set-up, production, idle

All times are measured in minutes

RESOURCE INFORMATION CUTTING MILLING

Set up time

Production time/pencil

Total Production time

Idle time (Available time- total set up time

- total prod. time)

2 3

6 2

Total Set up time

6 x 600

----- 3 x 600

2 x 600

7000-2-6x600 = 3398 3398-3x600-2x600 = 398

CALCULATIONS REGARDING INFORMATION CONTENT OF IPs IN

DIFFERENT STATESInformation ParametersCutting

States Set up Production Idle

Probabilities 2/7000= 0.00029

3600/7000= 0.5143 3398/7000= 0.4854

States

Probabilities

Set up Production

Idle

Milling

1800/3398= 0.2571 1200/3398= 0.6857 398/3398= 0.5714

Information Content (H) 0.0034 0.4934 0.5062

‘H’ for Cutting 0.4968

Information Content (H)

‘H’ for Milling

0.4856 0.5303 0.3623

1.0159

RESULTS

Complexity Index (CI) of Machining activity (sub-activity)

= Information Content associated with the information parameters (IPs) at various states of machining

= 0.4968 + 1.0159

=1.5127

Overall Complexity Index (OCI)= Summation of CIs for all the design activities involved in the manufacture of a pencil

DISCUSSIONS

• Complexity Measurement» Inherent Variety

» Uncertainty on account of variety

• CI measurement does not indicate the cause of complexity

• Design Activities can be distinguished on the basis of the CI

• Occurrence of idle state results in reduced complexity

CONCLUSIONS

• COMPLEXITY INDEX OF A DESIGN ACTIVITY IS MEASURABLE TO A CERTAIN EXTENT WITHIN THE STATED ASSUMPTIONS

• COMPLEXITY OF DESIGN ACTIVITY IS DEPENDENT ON THE AMOUNT OF INFORMATION CONTENT ASSOCIATED WITH ITS INFORMATION PARAMETERS(IPs)

LIMITATIONS

• PROCESS SPECIFIC

• INFORMATION DEPENDENT

• VARIABLE RESULTS

• PROCESSING TIME

FUTURE WORK

• Information Parameters (IPs) with reference to other CGFs have to be identified and implemented

• Extend the model in the area of project management

• Modification of the equation used