Linear regression on an usual domain, hyperplane, sphere or simplex. The problem I have in mind is as follows: I try to reverse-engineer the recipe for the coca cola beverage. The response, Y, is how close my recipe is to the actual formula, based on a number of tastings performed by a number of different people, according to a design of experiment plan. Indeed, it's quite similar to a clinical trial where a mix of atoms or chemical radicals (each combination producing a unique molecule) is tested to optimize a drug. The independent variables are binary, each one representing an ingredient: salt, water, corn syrup etc. Read more at http://bit.ly/18PDU7e Can someone provide guidance on how best to proceed? You may leave the list at any time by sending the command SIGNOFF allstat to [log in to unmask], leaving the subject line blank.