Confidence Interval for Site Index Using Curves Based on Stem Analyses

1971 ◽  
Vol 1 (4) ◽  
pp. 241-245 ◽  
Author(s):  
L. Heger
Keyword(s):  
Confidence Interval ◽  
Sample Size ◽  
Confidence Intervals ◽  
White Spruce ◽  
Site Index ◽  
Stand Age ◽  
Average Quality ◽  
Breast Height ◽  
True Value ◽  
Index Level

A method was described for the derivation of confidence intervals for site index using site-index curves based on stem analyses. The method allows assessment of effects on index estimates due to stand age, index level, sample size of heights used in entering the curves, index age, and sample size underlying the curves. Of these effects, the first three were evaluated for a set of curves based on stem analyses of white spruce (Piceaglauca (Moench) Voss) and on index age of 50 years at breast height (BH). With sample averages of 20 heights, about 95% of index estimates were within ±5 ft (1.52 m) of the true value in spruce 25–100 years old at BH on both average quality and extreme quality sites. To ensure this precision in spruce younger than 15 years at BH, 50 heights were required on the average sites and more than 50 on extreme sites.

Effect of Index Age on the Precision of Site Index

1973 ◽  
Vol 3 (1) ◽  
pp. 1-6 ◽  
Author(s):  
L. Heger
Keyword(s):  
Confidence Interval ◽  
Random Error ◽  
White Spruce ◽  
Site Index ◽  
Regression Method ◽  
Curve Shape ◽  
Breast Height

Effect of index age on the probable size of random error in site index was evaluated by comparing the 95% confidence interval for site index by curves based on index age 50 years at breast height (BH) with that by curves based on index age 100 years at BH. The curves were constructed using the regression method and stem analyses of 181 dominant white spruce trees (Piceaglauca (Moench) Voss). Using curves based on index age 100, a 10-ft index class could not be identified with 95% confidence for BH ages below about 50 years even if these curves were entered with sample averages of 50 dominant heights. Using curves based on index age 50, a 10-ft index class could be identified with 95% confidence for BH ages 20–100 years if these curves were entered with sample averages of at least 15 dominant heights. Effect of index age on the outcome of curve shape comparisons was discussed.

scholarly journals Site-index Curve Shape in Spruce

1969 ◽  
Vol 45 (3) ◽  
pp. 184-186 ◽  
Author(s):  
L. Heger
Keyword(s):  
Picea Glauca ◽  
Black Spruce ◽  
White Spruce ◽  
Site Index ◽  
Absolute Difference ◽  
Curve Shape ◽  
Breast Height ◽  
Maximum Absolute Difference ◽  
Site Index Curve ◽  
Index Curve

Sets of site-index curves were prepared from stem analyses of white spruce (Picea glauca (Moench) Voss) and black spruce (P. mariana (Mill.) BSP.) from various regions in the boreal forest of Canada. Ordinates of the site-index curves, computed for 5-year breast-height age intervals up to 75 years, and for 10-foot site-index intervals up to 70 feet, were compared within the species for the same values of site index and age. For breast-height ages below 55 years and for site index below 70 feet, the maximum absolute difference among the ordinates did not exceed 2.0 feet in white spruce, and 1.6 feet in black spruce; the corresponding average deviations were 0.75 and 0.80 feet. For breast-height ages above 55 years, these differences increased with age and, at 75 years, reached 8.8 feet in white spruce, and 3.8 feet in black spruce; the corresponding average deviations were 4.40 and 1.53 feet.

Explorations in statistics: confidence intervals

2009 ◽  
Vol 33 (2) ◽  
pp. 87-90 ◽  
Author(s):  
Douglas Curran-Everett
Keyword(s):  
Confidence Interval ◽  
Confidence Intervals ◽  
Hypothesis Test ◽  
Statistical Information ◽  
Experimental Result ◽  
P Value ◽  
Population Parameter ◽  
True Value ◽  
Level Of Confidence ◽  
The Mean

Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This third installment of Explorations in Statistics investigates confidence intervals. A confidence interval is a range that we expect, with some level of confidence, to include the true value of a population parameter such as the mean. A confidence interval provides the same statistical information as the P value from a hypothesis test, but it circumvents the drawbacks of that hypothesis test. Even more important, a confidence interval focuses our attention on the scientific importance of some experimental result.

scholarly journals Sample size for estimating average trunk diameter and plant height in eucalyptus hybrids

2016 ◽  
Vol 46 (7) ◽  
pp. 1192-1199 ◽  
Author(s):  
Alberto Cargnelutti Filho ◽  
Rafael Beltrame ◽  
Dilson Antônio Bisognin ◽  
Marília Lazarotto ◽  
Clovis Roberto Haselein ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Confidence Interval ◽  
Sample Size ◽  
Plant Height ◽  
Tree Height ◽  
Trunk Diameter ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Variance Homogeneity ◽  
Mean Variance

ABSTRACT: In eucalyptus crops, it is important to determine the number of plants that need to be evaluated for a reliable inference of growth. The aim of this study was to determine the sample size needed to estimate average trunk diameter at breast height and plant height of inter-specific eucalyptus hybrids. In 6,694 plants of twelve inter-specific hybrids it was evaluated trunk diameter at breast height at three (DBH3) and seven years (DBH7) and tree height at seven years (H7) of age. The statistics: minimum, maximum, mean, variance, standard deviation, standard error, and coefficient of variation were calculated. The hypothesis of variance homogeneity was tested. The sample size was determined by re sampling with replacement of 10,000 re samples. There was an increase in the sample size from DBH3 to H7 and DBH7. A sample size of 16, 59 and 31 plants is adequate to estimate DBH3, DBH7 and H7 means, respectively, of inter-specific hybrids of eucalyptus, with amplitude of confidence interval of 95% equal to 20% of the estimated mean.

Modelling survival probability of individual trees in Norway spruce stands under different thinning regimes

2005 ◽  
Vol 35 (1) ◽  
pp. 113-121 ◽  
Author(s):  
Kjell Karlsson ◽  
Lennart Norell
Keyword(s):  
Norway Spruce ◽  
Goodness Of Fit ◽  
Basal Area ◽  
Site Index ◽  
Stand Age ◽  
Goodness Of Fit Test ◽  
Individual Tree ◽  
Thinning Intensity ◽  
Diameter At Breast Height ◽  
Breast Height

The probability that an individual tree will remain in even-aged Norway spruce (Picea abies (L.) Karst.) stands subjected to different thinning programmes was modelled, using data from a thinning experiment established in 25 localities in southern Sweden. A logistic regression approach was used to predict the probability and the Hosmer–Lemeshow goodness-of-fit test to evaluate the fit. Diameter at breast height (DBH), quadratic mean DBH, thinning intensity, thinning quotient, basal area, number of stems per hectare, stand age, number of thinnings, and site index were used as explanatory variables. Separate analyses for stands thinned from below, stands thinned from above, and unthinned stands were performed. The modelled probability graphs for trees not being removed, plotted against their diameter at breast height, had clear S-shapes for both unthinned stands and stands thinned from below. The graph for stands thinned from above was bell-shaped.

Research on the Confidence Interval of Indirect Detection

2011 ◽  
Vol 418-420 ◽  
pp. 532-535
Author(s):  
Hai Bin Chen ◽  
Nan Ge ◽  
Xiao Jun Tong
Keyword(s):  
Confidence Interval ◽  
Confidence Intervals ◽  
Concrete Strength ◽  
Interval Estimation ◽  
Point Estimation ◽  
Indirect Detection ◽  
Detection Methods ◽  
Theoretical Formula ◽  
True Value ◽  
Practical Engineering

Abstract. Using the correlation between the measure value and measured value in the indirect detection, the whole presumption method and theoretical formula of the confidence intervals for measured value are put forward. Based on the different detection methods, the confidence interval of high confidence and high accuracy can be given by the proposed method according to random measurement results. Through the Monte Carlo simulation, using the deducing method and the related theory, it may be concluded that the true value is included within the confidence interval which is obtained by this method. The traditional method can only get the point estimation but not give the confidence intervals in the practical engineering. According to the method, the interval estimation of concrete strength can be give. Moreover, this method is used not only in test concrete strength, especially in the evaluation of earthquake, but also in strength detecting for bridges, the pressure vessel, aircraft wing etc.

scholarly journals Parameter Estimation of Inverse Rayleigh Distribution under Competing Risk Model for Masked data

2015 ◽  
Vol 20 (2) ◽  
pp. 122-127 ◽  
Author(s):  
M.S. Panwar ◽  
Bapat Akanshya Sudhir ◽  
Rashmi Bundel ◽  
Sanjeev K. Tomer
Keyword(s):  
Sample Size ◽  
Mean Square Error ◽  
Confidence Intervals ◽  
Risk Model ◽  
Life Time ◽  
Real Data ◽  
Rayleigh Distribution ◽  
Mean Square ◽  
True Value ◽  
The Mean

This paper tries to derive maximum likelihood estimators (MLEs) for the parameters of the inverse Rayleigh distribution (IRD) when the observed data is masked. MLEs, asymptotic confidence intervals (ACIs) and boot-p confidence intervals (boot-p CIs) for the lifetime parameters have been discussed. The simulation illustrations provided that as the sample size increases the estimated value approaches to the true value, and the mean square error decreases with the increase in sample size, and mean square error increases with increase in level of masking, the ACIs are always symmetric and the boot-p CIs approaches to symmetry as the sample size increases whereas the mean life time due to the local spread of the disease is less than that due to the metastasis spread in case of real data set.Journal of Institute of Science and Technology, 2015, 20(2): 122-127

How Many Tree Heights Should You Measure for Natural, Atlantic Coastal Plain Loblolly Site Index?

1981 ◽  
Vol 5 (4) ◽  
pp. 180-183 ◽  
Author(s):  
F. Thomas Lloyd
Keyword(s):  
Sample Size ◽  
Loblolly Pine ◽  
Coastal Plain ◽  
Site Index ◽  
Atlantic Coastal Plain ◽  
Stand Age ◽  
Site Class ◽  
Pinus Taeda L ◽  
Relationship Of ◽  
Atlantic Coastal

Abstract Sample size is tabulated for the number of tree heights needed to site-classify plots growing natural, Atlantic coastal plain loblolly pine (Pinus taeda L.). The size of the sample depends on observed stand age and selected site-class size, index age, and classification success rate. The most important outcome is the relationship of sample size to stand age because putting it into practice results in uniformly reliable site-index estimates.

scholarly journals Site-Index Curves and Growth Intercepts for Young White Spruce Plantations in North Central Ontario

2006 ◽  
Vol 23 (4) ◽  
pp. 257-263 ◽  
Author(s):  
Willard H. Carmean ◽  
Gerrit Hazenberg ◽  
James S. Thrower ◽  
Richard R. LaValley
Keyword(s):  
Regression Model ◽  
Nonlinear Regression ◽  
White Spruce ◽  
Analysis Data ◽  
Site Index ◽  
Nonlinear Regression Model ◽  
North Central ◽  
Breast Height ◽  
University Of Wisconsin ◽  
Dominant Height

Abstract Site-index (heightߝgrowth) curves, site-index prediction equations, and growth intercepts were developed from internode measurements and stem-analysis data using dominant trees in 69 plots located in white spruce plantations aged 19 to 32 years total age. Site-index curves were based on breast-height (1.3 m) age because our analyses show that height growth below breast height is slow and erratic and is poorly related to site index (dominant height at 15 years breast-height age). The most precise model for computing heightߝgrowth curves was a Newnham constrained polymorphic expression (Newnham, R.M. 1988. A modification of the Ek-Payandeh nonlinear regression model for site-index curves. Can. J. For. Res. 18:115ߝ120) of the Ek nonlinear regression model (Ek, A.R. 1971. A formula for white spruce site-index curves. University of Wisconsin For. Res. Note 161. 2 p). Comparisons showed that site-index curves in North Central Ontario were comparable to site-index curves for white spruce plantations in southeastern Ontario. The first three to five internodes above 2.0 m gave the most precise estimates of site index based on growth intercepts. North. J. Appl. For. 23(4):257–263.

Growth intercepts for estimating site quality of young white spruce plantations in north central Ontario

1987 ◽  
Vol 17 (11) ◽  
pp. 1385-1389 ◽  
Author(s):  
James S. Thrower
Keyword(s):  
Average Length ◽  
White Spruce ◽  
Site Index ◽  
Site Quality ◽  
North Central ◽  
Breast Height

Growth intercepts were used to estimate site index (defined as height of the trees 15 years after breast height (1.3 m) was attained) of dominant, planted white spruce (Piceaglauca (Moench) Voss) in north central Ontario. The growth intercepts were computed using four methods to select internode lengths from series of one through seven internodes, starting at each of eight heights from 0 to 3.0 m. Precision increased rapidly with more internodes and higher starting heights but quickly slowed to only marginal increases. Removing the smallest internode increased precision when growth intercepts started below 1.3 m. Removing the largest and both the smallest and largest internodes reduced precision from all starting heights. The most precise and practical growth intercepts used the average length of the first three, four, and five internodes above 2.0 m, explaining 83, 85, and 89% of the variation in site index, respectively.

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