Final answer:
Researchers determine the effectiveness of a new WiFi range booster by comparing routers' performance with and without the booster. If the booster consistently extends the range, it's considered effective in enhancing WiFi connectivity.
Step-by-step explanation:
When assessing if a new WiFi range booster is effective, researchers can compare the native range of routers without the booster to the range with the booster under the same conditions. If the ranges recorded with the booster are significantly greater than those without, it can be concluded that the WiFi range booster has improved WiFi performance and coverage. The trial with 12 different routers would provide a data set from which to draw conclusions about the booster's performance.