The PENT value for a resin may be estimated within ±10% by determining the % of heat flow to melt a fraction of a polymer above or below a set point and comparing it to a graph or algorithm of PENT values related to the % of heat flow to melt entire sample for a number of resins made using the same catalyst system. In a similar manner one may estimate the process conditions to prepare a polymer having a target PENT value based on the conditions used to prepare the samples for the graph or algorithms. The invention provides a simple procedure that may be used at a manufacturing site to estimate PENT values.