Forestry officials have recently opened up a new parcel of land to reafforestati
ID: 3305290 • Letter: F
Question
Forestry officials have recently opened up a new parcel of land to reafforestation but are concerned about the quality of the land to support good growth in Pinus Radiata. Seedlings were planted in both the exisiting reserve and the new parcel of land. Heights of seedlings (in centimetres) were measured after 8 months and growth compared. The results are given below Old Plot New Plot 166 156 160 169 167 170 169 155 158 163 156 143 151 172 156 160 156 136 157 157 150 161 156 173 (b) Perform a parametric test of the above hypotheses and draw conclusions based on the P-value of the test (c) Perform a non-parametric test to analyze the same data. (d) State all underlying assumptions for the tests in parts (b) and (c) and comment on the similarities/differences in the outcomes of the testsExplanation / Answer
parametric test:
Two-Sample T-Test and CI: old plot, new lot
Two-sample T for old plot vs new lot
N Mean StDev SE Mean
old plot 10 163.30 5.70 1.8
new lot 16 156.25 9.07 2.3
Difference = (old plot) - (new lot)
Estimate for difference: 7.05
95% CI for difference: (1.06, 13.04)
T-Test of difference = 0 (vs ): T-Value = 2.43 P-Value = 0.023 DF = 23
nonparametric test:
Mann-Whitney Test and CI: old plot, new lot
N Median
old plot 10 164.50
new lot 16 156.00
Point estimate for 1 - 2 is 7.00
95.2 Percent CI for 1 - 2 is (-0.00,13.00)
W = 172.5
Test of 1 = 2 vs 1 2 is significant at 0.0512
The test is significant at 0.0495 (adjusted for ties)