A method, article of manufacture, and apparatus for processing continuous value data is disclosed. Data values stored in a database reflect a measurement of the value obtained for a specific point in time. In order to correlate the evaluation of two or more conditions, when measurements for each condition recorded at the same points in time are unavailable, embodiments of the invention provide a method for generating approximations of the unavailable values for comparison with others. Thereafter, a comparison between values for the points in time may be used to correlate the two conditions during query processing.