|Percentage of Decline
How to use this calculator:
The table helps determine how many pieces must be mailed to get a statistically
valid test result. There are two factors to consider: percent of decline (top
line) and confidence level (first vertical column at left). Many mailers prefer
testing at an 85 percent confidence level with a 12.5 percent decline.
Confidence Level - the percentage of time that a result can be expected
Percentage of Decline
- the percent that an original result can vary on subsequent mailings.
If you have any further questions or comments about this calculator, please
contact Edith Roman Associates.