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"Project: M4"., This report demonstrates how the large numbers of permanent plots established during the course of the NZFS standard inventory method can be used to improve the precision of both the inventory and the increment using a Continuous Forest Inventory method. A population of Douglas fir in Kaingaroa, stratified into 2 strata, was measured in 1969 and again in 1974. No permanent growth plots were actually demarcated, but 18 of the plots in the 1969 inventory were relocated in 1974 so that pairs of observations were obtained in addition to the temporary unmatched plots. The analysis, called sampling with partial replacement using multiple regression, is detailed step by step and Hewlett Packard programs in BASIC are presented. The 1969 inventory was improved by a 25% reduction in the confidence limits over simple stratified random sampling, while the confidence limits of the estimate of growth were reduced by 50%. The confidence intervals were less than 5% of the mean of the two inventories and 13% of the mean for the increment.