A method of reducing carryover of (a) reagents in analytical testing in a testing apparatus using multiple reagents, comprising: providing an incubation member including receptacles including a first subset of reaction vessels and a second subset of reaction vessels; dispensing a first reagent in only the first subset of the reaction vessels for all tests of a first test type that include addition of the first reagent; and dispensing a second reagent in only the second subset of the reaction vessels for all tests of a second test type that include the addition of the second reagent, wherein the incubation member comprises an annular ring, characterized in pre-assigning the first and second subset of reaction vessels, that certain test types are pre-assigned in accordance with a pattern of the receptacles of the incubation member and recording the position of each reaction vessel in a memory of a controller which controls rotation of the incubation member such that reagents which may interfere with another reagent are never provided in the same subset, or (b) sample liquids in analytical testing, comprising: providing an incubation member including a plurality of reaction vessels thereon; pre-assigning a first subset of the reaction vessels for only a first test type for all test lots; and pre-assigning a second subset of the reaction vessels for only a second test type for all test lots, the first test type being different than the second test type, wherein the incubation member comprises an annular ring, characterized in recording the position of each reaction vessel in a memory of a controller which controls rotation of the incubation member, that certain test types are pre-assigned to be placed in a pattern on the incubation member, and dispensing a first reagent in only the first subset of the reaction vessels for all the tests of the first test type that include addition of the first reagent; and dispensing a second reagent in only the second subset of the reaction vessels for all tests of the second test type that include the addition of the second reagent such that reagents which may interfere with another reagent are never provided in the same subset. (a) reagents in analytical testing in a testing apparatus using multiple reagents, comprising: providing an incubation member including receptacles including a first subset of reaction vessels and a second subset of reaction vessels; dispensing a first reagent in only the first subset of the reaction vessels for all tests of a first test type that include addition of the first reagent; and dispensing a second reagent in only the second subset of the reaction vessels for all tests of a second test type that include the addition of the second reagent, wherein the incubation member comprises an annular ring, characterized in pre-assigning the first and second subset of reaction vessels, that certain test types are pre-assigned in accordance with a pattern of the receptacles of the incubation member and recording the position of each reaction vessel in a memory of a controller which controls rotation of the incubation member such that reagents which may interfere with another reagent are never provided in the same subset, or (b) sample liquids in analytical testing, comprising: providing an incubation member including a plurality of reaction vessels thereon; pre-assigning a first subset of the reaction vessels for only a first test type for all test lots; and pre-assigning a second subset of the reaction vessels for only a second test type for all test lots, the first test type being different than the second test type, wherein the incubation member comprises an annular ring, characterized in recording the position of each reaction vessel in a memory of a controller which controls rotation of the incubation member, that certain test types are pre-assigned to be placed in a pattern on the incubation member, and dispensing a first reagent in only the first subset of the reaction vessels for all the tests of the first test type that include addition of the first reagent; and dispensing a second reagent in only the second subset of the reaction vessels for all tests of the second test type that include the addition of the second reagent such that reagents which may interfere with another reagent are never provided in the same subset.