The invasive diatom species Didymosphenia geminate has the potential to inflict substantial ecological and economic damage in rivers. The article "Substrate Characteristics Affect Colonization by the Bloom- Forming Diatom Didymosphenia geminata" (Acquatic Ecology, 2010: 33-40) described an investigation of colonization behavior. One aspect of particular interest was whether the roughness of stones impacted the degree of colonization. The authors of the cited article kindly provided the accompanying data on roughness ratio (dimensionless) for specimens of sandstone and shale.

Normal probability plots of both samples show a reasonably linear pattern. Estimate the difference between true average roughness for sandstone and that for shale in a way that provides information about reliability and precision, and interpret your estimate. Does it appear that true average roughness differs for the two types of rocks (a formal test of this was reported in the article)?

Transcribed Image Text:

Sandstone 5.74 2.07 3.29 0.75 1.23 2.95 1.58 1.83 1.6 1.12 2.91 3.22 2.84 1.97 2.48 3.45 2.17 0.77 1.44 3.79 56 84 40 .55 .36 .72 Shale 29 47 66 48 .28 72 31 .35 .32 .3743 60 54 4351