Statistics Solutions

[See Steps] Hardwood trees are harvested in a selective manner for the manufacture of fine furniture. Environmental groups are concerned that as few trees

Question: Hardwood trees are harvested in a selective manner for the manufacture of fine furniture. Environmental groups are concerned that as few trees are selected for cutting as possible while companies feel that they need a certain amount of wood for manufacturing. To help each group predict the volume of lumber in a selected tree, various measurements are made before the tree is cut. Unfortunately, volume is not easily determined before harvesting.

Two common measurements made before cutting down the tree are DBH (the diameter of the tree at breast height, 4.5 feet off the ground) and the height of the tree measured with sighting instruments. After the tree is harvested the volume of lumber may be measured.

Both groups believe that a regression model relating volume to diameter and/or height will be helpful. The data file below gives the diameters, heights, and volumes of 31 trees harvested in the Allegheny National Forest in Pennsylvania.

The data are contained in the file Wood.xlsx .

  1. Estimate the two simple regression models and the multiple regression model that are appropriate for these data based upon the description above. This will require you to conduct three separate regressions. DO NOT try to use any other model for the volume estimate. There are other models available but for the purpose of this assignment you are limited to the models described above.
  2. Which of the three models would you recommend that the two groups use? Why? HINT : you should analyze the correlation matrix to answer this question.
  3. A specific tree with a height of 62 feet and a diameter of 17.9 inches has just arrived at the mill. DO you believe your model is appropriate for making a point estimate for this tree? What volume can be expected? Build a 95% confidence interval for the volume of this tree.
    Price: $2.99
    Solution: The downloadable solution consists of 6 pages
    Deliverable: Word Document


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