Techniques for quantifying the quality of trend lines. A method includes defining a collection of reference data sets derived from multiple historical projects in a similar subject area as the target project, defining one or more indicators of data set applicability to a target project estimation, said defining based on multiple characteristics of the target project, evaluating applicability of each of the reference data sets based on the one or more indicators, and identifying one or more of the reference data sets as applicable for use in the target project estimation.