Activity 9Response Measure Straw Man

The goal of a response measure straw man is to give stakeholders something to beat up until they arrive at their own answers. We do this by inventing a reasonable response measure for some quality attribute scenario as a way to kickstart discussions. The straw man technique works with other architecturally significant requirements discussed in Chapter 5, Dig for Architecturally Significant Requirements.

Benefits

  • Provides an example of a measurable response and response measure
  • Jump-starts thinking about quality attribute scenarios
  • Overcomes blank-page syndrome by providing something to edit instead of creating response measures from scratch

Activity Timing

Varies, often combined with other activities

Participants

Architects will often create straw man response measures on their own and validate with stakeholders later.

Preparation and Materials

Steps

  1. For each quality attribute scenario, make up a response and response measure. The response should be a reasonable, best guess based on your knowledge and experience. Response measures can be either outrageous or honest.

    • Choose an honest response measure when you think you can confidently estimate a good measure.

    • Choose an outrageous response measure when your confidence is low to help find the boundaries around acceptable behavior.

  2. Label the scenarios as having a straw man response measure to avoid potential future confusion.

  3. Validate the scenarios and their response measures with stakeholders, such as during a stakeholder interview, described, or mini-QAW, described.

Guidelines and Hints

  • Use a straw man to understand the boundaries around acceptable behavior.

  • Responses should be correct for the scenario. The point is to zero in on an accurate and reasonable response measure.

  • Listen to your stakeholders once you get them talking. When presented with a wrong answer, many stakeholders will react with useful information.

  • Keep an eye out for anchoring. Anchoring is a cognitive bias where people let the first information they hear drive their decision making. The straw man should be a reasonable estimate or so outrageous it will be rejected outright. Exercise caution if your outrageous estimate is accepted.

Example

Here are some examples of response measure straw men created for a cloud-based information system:

Quality Attribute

 Response

Straw Man Response Measure

Accepted Response Measure

Changeability

Time required to add a new algorithm

6 months

2 iterations

Portability

Effort required to move to new cloud provider

3 person-months

4 person-days

Performance

Average response time under typical load

1 minute

3 seconds max

Scalability

User load the system should be able to handle

10 requests per second

140 requests per second

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