Comparison of natural durability of wood by stake tests followed by survival analysis

Abstract The conventional stake test is widely used to evaluate wood durability. monitors the deterioration level observed on stakes partially inserted into ground. results are conventionally expressed as relationship between mean and exposure periods. Durability compared groups based results; however, there no scientific basis for comparison. To include a test, we applied survival analysis it. Four were subjected at three sites 7 years. levels monitored according procedure, was data. Kaplan–Meier curves plotting probabilities against periods indicated that durability of Japanese cedar heartwood higher than those sapwood. However, it also demonstrated ratio sapwood strongly dependent sites. It revealed portion did not differ significantly among cedar, cypress, larch. These verified using modified Gehan–Wilcoxon test.