{"id":"upadhyay-2024-h-quadratic","source":{"id":"upadhyay-2024","citation":"Upadhyay, J., & Khadka, S. (2024). Modelling height-diameter relationship of Pinus roxburghii in Nepal. American Journal of Biological and Environmental Statistics, 10(3), 49–59.","title":"Modelling Height-Diameter Relationship of Pinus Roxburghii in Nepal","authors":["Upadhyay, J.","Khadka, S."],"year":2024,"venue":"American Journal of Biological and Environmental Statistics","doi":"10.11648/j.ajbes.20241003.12","url":"https://doi.org/10.11648/j.ajbes.20241003.12","read_url":"http://article.sciencepg.com/pdf/j.ajbes.20241003.12","access":"open","checked_at":"2026-11-02","status":"current"},"name":"Chir pine height from D, quadratic (M2)","output":{"quantity":"height"},"expression":"1.1052804 + 0.6252304 * D - 0.0021242 * D^2","published":{"expression":"1.1052804 + 0.6252304 * DBH - 0.0021242 * DBH^2","units":{"DBH":"cm"},"variables":{"DBH":"D"},"output_unit":"m"},"taxon":{"level":"species","name":"Pinus roxburghii","family":"Pinaceae","group":"conifer"},"region":{"scope":"national","countries":["NP"],"place":"Nepal, Forest Resource Assessment 2018 plots","biomes":["subtropical","montane"]},"stand":"natural","fit":{"r2":0.72,"method":"polynomial (degree 2) regression"},"evidence":[{"field":"expression","quote":"height=1.1052804+0.6252304*dbh−0.0021242*dbh2","locator":"Table 4, M2"}],"check":[{"inputs":{"D":10},"expected":7.1452,"origin":"computed","note":"computed from the published form (coefficients as printed)"},{"inputs":{"D":25},"expected":15.4084,"origin":"computed","note":"computed from the published form (coefficients as printed)"},{"inputs":{"D":50},"expected":27.0563,"origin":"computed","note":"computed from the published form (coefficients as printed)"}],"verification":"original_read","checked_at":"2026-11-02","notes":"r2 is the adjusted R2 as printed in Table 6 (RMSE 3.639). Fitted on the 80% training split of the FRA 2018 sample; the paper's n is ambiguous (610 'sample plots' vs 610 trees in Table 3), so n_trees and ranges are left out. Table 6 coefficient columns differ from Table 4; Table 4 (printed formulas, consistent with Table 3 class means) is used."}