Effectiveness of principal component analysis for analyzing particleboard subjected to outdoor exposure

Abstract

In order to investigate the strength reduction of particleboards subjected to outdoor exposure at eight sites across Japan, the climate factors, i.e., temperature, sunshine duration, and precipitation were analyzed using a principal component analysis. The first principal component (PC1) had an eigenvalue of 2.31 and a proportion of 76.9 %, indicating that the PC1 combines the climate factors into one factor. All of the PC1 eigenvectors demonstrated high, positive values for each climate factor, demonstrating that the first principal component score (PC1 score) increases with increasing temperature, sunshine duration, and precipitation. The PC1 score was introduced as a new index for evaluating strength reduction, as the strength shows a strong correlation with the PC1 score: a higher PC1 score was linked to lower particleboard strength after the outdoor exposure test. The PC1 score can be calculated directly and unambiguously using the climate factors; further, the PC1 score was found to be a more powerful index than each individual climate factors or a combination of them.

Comparison between climatic factors and climate deterioration index on strength reduction of particleboards subjected to various climatic conditions in Japan

“…The eight sites selected were Asahikawa, Noshiro, Morioka, Tsukuba, Maniwa, Okayama, Shizuoka, and Miyakonojo (Table 1). Recently results have been reported by the authors' research group (Korai et al , 2014aKorai 2012;Korai and Hattori 2013;Korai and Saotome 2014;Watanabe et al 2014;Korai and Watanabe 2015;Kojima et al 2009Kojima et al , 2012Kojima and Suzuki 2011a, b;Sekino et al 2014).…”

“…Instead of separate climatic factors, the CDI was developed as a simple and useful climate index (Korai and Watanabe 2015). This section explains that the CDI is simpler and more useful than each climatic factor separately using ANCOVA.…”

“…Thus, in a previous study by the authors, the three climatic factors were combined into a first principal component using principal component analysis (Korai and Watanabe 2015). The score of the first principal component was closely related to the strength reduction.…”