Question

researchers would like to assess the overall health of white pine trees in a state park. the park has a paved road that runs through the middle of the park. to select trees to assess for damage, the ranger parks at the side of the road and chooses 100 trees near the road to assess for damage. which of the following statements best describes the bias that may arise from the results?

• because only 100 trees were selected, the overall damage of trees in the park may be underestimated.
• the ranger should take another sample of trees near the road and compare it to the first sample to reduce bias.
• because a random sample of trees was chosen, the sample should provide a suitable estimate of the overall health of the trees.
• trees near the road may have more damage than trees away from it, so the results may overestimate the overall damage of the trees.

Explanation:

The sampling method here is non - random as only trees near the road are chosen. Trees near the road may have different damage levels (e.g., due to pollution from traffic, more human interference) compared to trees away from the road. If trees near the road have more damage, then using only these trees to estimate the overall damage of all trees in the park will lead to an overestimation of the overall damage.

• Option 1: The issue is not the sample size (100 trees) but the sampling bias, so this is incorrect.
• Option 2: Taking another sample of trees near the road still doesn't address the bias of only sampling near - road trees, so this is incorrect.
• Option 3: The sample is not random (only near - road trees), so it won't provide a suitable estimate, this is incorrect.
• Option 4: Correctly identifies the sampling bias as trees near the road may have more damage, leading to overestimation of overall damage.

Answer:

D. Trees near the road may have more damage than trees away from it, so the results may overestimate the overall damage of the trees. (assuming the options are labeled A, B, C, D with D being the last option as per the description)