Winston 在进行增量测试之前检查其目标客户的预估规模。他要尽量将哪种风险降至最低？

Winston is trying to minimize the risk of having a target audience that is too small, which would cause the ad reach to be reduced by the control group. In incrementality testing, a portion of the target audience is held out as a control group, meaning they do not see the ad. If the initial target audience is already small, further reducing the exposed group by creating a control group can make the exposed group too small to achieve statistically significant results or to accurately measure the incremental impact. A target audience that is too large (the incorrect option) would not dilute results; instead, it would provide more data, potentially leading to more robust findings, though it might increase costs.