Exactly. The word of the day is “baseline”.
What we can measure are trends—increasing or decreasing number of poison pen letters, or cases where within 12 months of landing under the spousal category the immigrant is sponsoring someone else as a spouse. It's that sort of measurement that will give you the trend. If the trend is stable and it's hitched to the baseline, you can take more risk. You instruct the visa officers, if in doubt, to allow more people forward. That's what's needed. The best solution is to accept risk.