The invasive diatom species Didymosphenia geminata has the potential to inflict substantial ecological and economic damage in rivers. The article “Substrate Characteristics Affect Colonization by the Bloom-Forming Didymosphenia geminata” (Aquatic Ecology, 2010: 33–40) described an investigation of colonization behavior. One aspect of particular interest was whether y = colony density was related to x = rock surface area. The article contained a scatterplot and summary of a regression analysis. Here is representative data:
a. Determine the equation of the least squares line for this data and then calculate and interpret the coefficient of determination.
b. The second observation has a very extreme y value (in the full data set consisting of 72 observations, there were 2 of these). This observation may have had a substantial impact on the form of the regression function and subsequent conclusions. Eliminate it and redo part (a). What do you conclude?
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