The difference between a linear regression and a correlation is largely philosophical. linear regression implies a causal relationship, while correlation does not. which of the following examples are best described as a correlation? a. the global mean temperature has gone up while the global pirate population has gone down. b. the roots of trees play a major role in preventing soil erosion. the more trees are cut down in a particular area, the greater the rate of erosion. c. the growth of trees is supported by environments with increased carbon dioxide concentration in the atmosphere. more carbon dioxide in the atmosphere as a result of fossil fuel burning has resulted in increased tree growth. d. when nitraie reacts with n-(1-naphthyl)ethylenediamine a purple pigment is produced. the amount of purple pigment produced increases with increasing nitrite concentration.