"In the marketing profession, statistics can be very deceiving to the human eye. Take for example, an email program where you are testing a specific aspect of your email(s). If your average click rate is 2% this means it can sway from 1.4% to 2.6% which is a pretty wide margin. The results for this test, show a click rate of 2.4% which is 20% higher than the average, however to the human eye, we quickly dismiss it because we've had 2.4% click rates before and move on our way. The only way to really know is to perform A/B tests, however, you also have to ensure that the results you are getting are statistically significant and most marketers don't have list sizes large enough so often make inaccurate assumptions. Another thing we often ask marketers to consider is even a measly 8% average uptick in results is similar to accomplishing in 12 months what used to take 13. The human eye absolutely can not see an 8% uptick without A/B testing and even then, they quickly dismiss it."