An ad for a new toothpaste, called TTP, says "Based on a 95% confidence level, our tests achieved between 1% and 8.7% reduction in plaque" as compared to other toothpastes on the market. What does 95% confidence level mean here? An ad for a new toothpaste, called TTP, says "Based on a 95% confidence level, our tests achieved between 1% and 8.7% reduction in plaque" as compared to other toothpastes on the market. What does 95% confidence level mean here? A mistake has been made because 95% + 8.7% is more than 100%. The tests include 95% of all toothpaste brands on the market. TTP toothpaste performs better than 95% of the other toothpastes. The interval from 1% to 8.7% covers 95% of the plaque improvements observed in the tests. TTP toothpaste estimates that the true improvement will be in the interval from 1% to 8.7% with 95% confidence