Ok... maybe he's right, but I'm suspicious about his methods. He's writing about his tools that they're "going for between $200 and $500.", then "This technique raised my sales from about $400 a month to $900 a month" and then that it raised the sales to $1500.<p>So basically he went from ~1.3 to ~2.6 then to ~4.3 sales a month. If he really measured the response, he should take the samples from at least one year (otherwise it would be season-dependant). He made changes in 2 steps - that means at least 2 years. So to me it looks like either:<p>- he improved the software over that time, his tools got more recognition among developers, standard business growth occurred, or<p>- he did nothing about his business or software, crisis and other events affecting sales didn't happen, world has been a controlled environment for a couple of years and 4 sales per month are statistically significant...<p>- or... Am I missing some option?