Due to the high cost of each experimental run in additive manufacturing (AM), there has been a drive to develop simulations that can find the optimal processing parameters. The accuracy of these simulations is dependent on the accuracy of the material parameters recorded in literature. These reported parameters can vary widely resulting in differing simulation results. For that reason, it is necessary to determine which parameters are the driving parameters. This will allow for only critical parameters to be experimentally found resulting in more accurate simulations faster. This article uses a Plackett-Burman design of experiment to screen for the material properties with the greatest effect on the results of a thermal mathematical model of a laser-based directed energy deposition (DED) AM process. It was found that variances in the absorption of the laser at 880 and 922 K along with variances in the thermal conductivity at 922 K have the largest effect on the range of the response variables that were used to characterize the melt pool. Having a smaller impact on the results are the thermal conductivity at 1491 K and the specific heat at 733 K, and the remainder of the factors have a negligible effect on the melt pool characteristics within the simulation.