Source Selection (weighted)

Weighted source selection is a method for choosing the best seller (a vendor or contractor bidding to do work for you) when you care about several things at once — not just price, but also quality, delivery time, experience, and so on. It turns a fuzzy 'who feels best?' decision into a clear, defensible number.

Here's how it works in words. First, list your evaluation criteria (price, quality, schedule, etc.) and give each one a weight — a number showing how important it is, with the weights usually adding up to 1 (or 100%). Next, score each seller on each criterion with a rating (say, 1 to 10). Then, for every seller, multiply each rating by its criterion's weight and add all those products together. That total is the seller's weighted score. The symbol Σ (the Greek letter sigma) simply means 'add up all of these.'

Reading the result is easy: the seller with the highest total score is the strongest overall match for what you value most. A higher weight means a criterion pushes the score more, so a seller who excels in the things you care about will rise to the top. Project managers use this to compare bids fairly, to justify their choice to stakeholders, and to avoid picking a vendor purely on the lowest price when quality or reliability matters more.