An interlaboratory comparison was undertaken by the ASTM Task Group responsible for C167, Standard Test Methods for Thickness and Density of Blanket or Baty Insulations. The purpose of this study was two-fold: determination of the most appropriate batt selection method and the development of a Precision and Bias statement. A pilot study revealed the need to revise the current batt selection technique for assessing the average recovered thickness for a package. This technique was shown to be a consistent underpredictor of package thickness, due to an overemphasis on pieces close to the outside edges of a package. The effect of end-compression was cited in the study as one which plays a significant role in the accuracy of a selection method. While the current ASTM selection method overaccounts for this phenomena by selecting the two end pieces as part of the 5-batt test sample, the previous study also showed that it is also possible to underaccount for end-compression and over-predict the average package thickness.