Which part? The fact that novice users have a hard time distinguishing between PPC and organic results? Anecdotal with the many novice users I have dealt with.

Which part? The fact that novice users have a hard time distinguishing between PPC and organic results? Anecdotal with the many novice users I have dealt with. That there is less advertising for software related keywords vs. other types of keywords? Try out Google's adwords traffic estimator: https://adwords.google.com/select/TrafficEstimatorSandbox https://adwords.google.com/select/TrafficEstimatorSandbox