FAST diagram of an electric kettle FAST stands for Function Analysis System Technique
Read to the right → to ask how? Read to the left ← to ask why? Everything between the two dashed lines is inside the study.
Function–cost matrix and value index
Split the kettle’s £12.40 manufacturing cost across its functions. Then estimate what each function is worth, meaning the cheapest way it could still be done reliably. The mismatches show up straight away. Value Index = cost ÷ worth. Anything above 2.0 is a target for the creative phase.
| Function (verb–noun) | Type | Cost £ | Worth £ | Value Index | Verdict | |
|---|---|---|---|---|---|---|
| Heat water | Basic | 4.20 | 4.20 | 1.00 | Healthy | |
| Contain water | Basic | 2.80 | 1.90 | 1.47 | Watch | |
| Control temperature | Secondary | 1.90 | 0.85 | 2.24 | Target | |
| Prevent scald | Required | 0.80 | 0.80 | 1.00 | Healthy | |
| Indicate status | Secondary | 0.60 | 0.15 | 4.00 | Attack | |
| Convey esteem | Esteem | 2.10 | 0.70 | 3.00 | Challenge | |
| Total product | 12.40 | 8.60 | 1.44 | −£3.80 gap |
“Indicate status” costs four times what it’s worth. That’s £0.45 a unit that could be saved on one line. “Control temperature”, at 2.24, is a target too. “Convey esteem”, meaning how premium the kettle looks, is worth questioning as well, but back it up with customer research rather than opinion. Multiply these gaps by the number of kettles made each year and this small table becomes the business case for the whole study. It’s how VE decides where to focus.
Learn it properly
Module 4 · Function Analysis & FASTFree, narrated and interactive — with a Certificate of Completion.