chapter  6
Statistical analysis results on the experiments’ outcomes
Pages 14

Tables 6.1 to 6.3 present the statistical analysis results of the bivariate correlation analysis in descending order. The ranges of statistical correlation adopted in this book are

1. No correlation when the correlation coefficient ranges from 0 to less than 0.1

2. Low correlation when the correlation coefficient ranges from 0.1 to less than 0.3

Table 6.1 Positively correlated design activities and strategies with the technical attributes of product success

Design activities/strategies Percentage of variation in

mobile robot performance (r2)

18-ACT Largest number of iterations in software

0.3**

1-STRA Shifting complexity 0.2** 29-ACT Modular testable interdeliverables 0.2** 14-STRA Considering reliability 0.2** 19-ACT Early verification 0.1** 13-STRA Fast response versus stability,

accuracy and payload 0.1**

36-ACT Modular deliverables and testing 0.1** 26-STRA Resource provisions 0.1** 25-ACT Multidisciplinary team 0.1** 27-STRA Modular testing 0.1** 31-STRA Decentralised decision making 0.1** 39-ACT Starting the design process as early

as possible and assigning time for presenting the outcome

0.1**

41-ACT Documenting the outcome of design discussions

0.1**

44-ACT Meeting collectively in conceptual rather than in detailed design

0.1**

49-ACT Predicting design progressive failure 0.1** 54-ACT Checking accuracy of

manufacturing 0.1**

60-ACT Quick testing of interdeliverables between modules

0.1**

2-STRA Simplest design 0.1** 12-ACT Top-down system structure

decomposition 0.1**

Table 6.2 Negatively correlated design activities and strategies with product success technical attributes

Design activities/strategies Percentage of variation in mobile

robot performance (r2)

62-ACT Testing aggregately the software subsystem at the end of the project rather than adopting quick testing

–0.3**

Table 6.3 Uncorrelated design activities and strategies with the technical attributes of product success

Design activities/strategies

3-ACT Choosing the mechanical design concept first 4-STRA Electronic distinguishing 5-STRA Only standard components 6-STRA Modular design 7-ACT Systematic design approach 8-ACT Quality of performing systematic design approach 9-STRA Error proof 10-STRA Tolerant design 11-STRA Maximising functionality and minimising iterations 15-STRA Considering maintainability 16-STRA Considering safety 17-STRA Error recovery 20-ACT Software team leader 21-ACT More time on conceptual and preliminary phases 22-ACT Reviewing similar designs 23-ACT Cross fertilisation of concepts among the team 24-ACT Time to aggregate plan 28-ACT More iterations in conceptual and preliminary phases 30-ACT Live meetings team in the conceptual and preliminary phases 32-STRA Sequential and concurrent design tasks 33-STRA More interested in meeting delivery deadline than in cost 34-ACT Estimating design activity duration 35-STRA Redeployment of human resources 37-ACT Coordinating the interrelated elements 38-ACT Conducting design research 40-STRA Considering critical path rather than critical chain 42-STRA Having experienced designers conceive assumptions of similar designs 43-STRA Having experienced designers prevent avoidable mistakes 45-ACT Meeting collectively in conceptual phase to choose the mechanical

and electronics concepts 46-ACT Conducting initial test experiments in the preliminary design phase 47-ACT Constructing to-scale cardboard prototype 48-ACT Strength-adaptable mechanical chassis 50-ACT Making sketches to generate concepts in the conceptual design phase 51-ACT Making computer-aided design (CAD) models in the preliminary

design phase 52-ACT Building to-scale prototype to be tested in real operational

environment

(Continued)

3. Moderate correlation when the correlation coefficient ranges from 0.3 to less than 0.6

4. High correlation when the correlation coefficient ranges from 0.6 to 1 (Cohen, 1988)

The positively correlated design activities and strategies to technical attributes of product success are presented in Table 6.1. The number that appears to the left of each design activity and strategy refers to its corresponding question in the relevant questionnaire as indicated in Appendices A, B and C. The design activities and strategies of positive correlation with technical attributes of product success should receive most focus and highest priority in resource allocation. This is determined according to their percentage of variation in technical performance due to the variable correlation coefficients with the technical performance attributes as a measure of success in the market, and according to their resulting p-value.