Lithographic apparatus focus test method and system, and device manufacturing method

A method and system for performing a focus test in a lithographic apparatus. According to the method, a substrate is provided with a layer of radiation sensitive material, the substrate is illuminated in the lithographic apparatus using a first focus sensitive feature and a second focus feature, and the substrate is analyzed to provide results of the focus test using the first focus sensitive feature as imaged on the substrate. The focus test is performed on a regular production wafer, and the results of the focus test are allowed if predetermined statistic properties associated with the second focus feature as imaged on the substrate are within predetermined limits. The second focus feature may be focus sensitive or focus insensitive.