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A Rationale-based Model for Architecture Design Reasoning

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7.2. An empirical study to validate the AREL model<br />

5. Present the AREL model to the experts and discuss the design reasoning captured by<br />

AREL.<br />

6. Compare the two sets of answers (with and without AREL support) to see if additional<br />

understanding are obtained with the use of the AREL model.<br />

7. Interview the expert to obtain additional comments on advantages and disadvantages<br />

of AREL modelling.<br />

7.2.3 Selecting experts<br />

Experts who were associated with the EFT system were asked to participate in this research.<br />

Use of expert opinion is dependendable because of the domain knowledge they<br />

possess [96]. We invited nine experts to participate (3 female and 6 male), all of whom<br />

have been working in this area <strong>for</strong> many years and can provide reliable assessment. On<br />

average, the experts have 16.6 years of IT experience (a maximum of 24 years and a minimum<br />

of 12 years), an average of 10.8 years of experience as an architect and designer (a<br />

maximum of 16 years and a minimum of 5 years), and an average of 7.7 years of experience<br />

in designing payment systems (a maximum of 18 years and a minimum of 1 year).<br />

The expert panels are selected <strong>for</strong> their experience with architecture design and their<br />

working in the electronic payment system field <strong>for</strong> a number of years. They are characterised<br />

by the following:<br />

• They have participated in the design, development and testing of the EFT systems<br />

or similar types of systems. There<strong>for</strong>e, they were familiar with the functionality of<br />

such payment systems.<br />

• They have had extensive design and development experience.<br />

• They are willing to commit needed time and ef<strong>for</strong>t.<br />

• They are willing to provide evaluations and interpretations of the new approach.<br />

Owing to the specialised background knowledge required and the confidentiality of the<br />

system, there is a limitation as to who can be recruited. Consequently, we decided to<br />

use non-probabilistic sampling techniques and convenience sampling method instead of<br />

random sampling [80]. Availability sampling operates by seeking responses from those<br />

people who meet the inclusion criteria. They are available and willing to participate in<br />

the research. The major drawback of non-probabilistic sampling techniques is that the<br />

results cannot be considered statistically generalisable to the target population, in this<br />

case software architects.<br />

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