Weighted Scoring Model
Also known as: weighted sum, scorecard, multi-criteria scoring.
Rates each candidate on several criteria, multiplies each rating by an agreed weight and adds them up. Trade-offs become explicit, and the answer depends on the weights.
Synthetic dataExamples on this page use synthetic data created for illustration.
Not adviceThis is educational material. It is not investment, business or other professional advice.
Definition
A weighted scoring model rates each candidate on several criteria, multiplies each rating by an agreed weight, and adds the results into one score. It makes trade-offs explicit and auditable, but the answer depends on the chosen criteria, scales and weights.
In plain terms
The method turns “which is better overall?” into arithmetic everyone can inspect: how much each criterion matters (the weights, usually adding to 1) and how each candidate does on it (the ratings, on a common scale). Because the calculation is open, a disagreement can be located: “we differ on how much delivery time matters”.
The weights are judgments, not facts, and the ranking can change when they change. Criteria that move together, such as price and quality signals, quietly count the same thing twice. Report how sensitive the ranking is to the weights, and keep the criteria and weights with each result (see Explainable Scoring).
Example
Three criteria rated 0 to 1 for two candidates.
| Weights set 1 | Weights set 2 | Rating X | Rating Y | |
|---|---|---|---|---|
| Price | 0.5 | 0.3 | 0.8 | 0.6 |
| Reviews | 0.3 | 0.5 | 0.6 | 0.9 |
| Delivery | 0.2 | 0.2 | 1.0 | 0.9 |
| Weights | Score X | Score Y | Winner |
|---|---|---|---|
| Set 1 (price matters most) | 0.78 | 0.75 | X |
| Set 2 (reviews matter most) | 0.74 | 0.81 | Y |
The ratings are identical; only the weights changed, and the winner flipped. A single score hides how much of the verdict is judgment about weights.
Common misunderstandings
- “The score is objective.” The arithmetic is exact, but the criteria, scales and weights are choices.
- “A higher score means better in an absolute sense.” It means better under these weights, among these candidates.
- “More criteria make it more accurate.” Overlapping criteria double-count and bury what matters.
References
- Valerie Belton, Theodor J. Stewart. Multiple Criteria Decision Analysis: An Integrated Approach . Springer, 2002. ISBN 978-0792375050.
- Ralph L. Keeney, Howard Raiffa. Decisions with Multiple Objectives: Preferences and Value Tradeoffs . Cambridge University Press, 1993. ISBN 978-0521438834.