Just passing the test didn’t guarantee a spot; there also was input from parents and teachers on whether the student possessed things like motivation, creativity, and adaptation. The threshold on the initial test was lowered slightly for disadvantaged “Plan B” students, who were either eligible for free or discounted lunches based on their family’s income, or were English-language learners.
Budget constraints resulted in the universal screening program getting curtailed substantially just two years later, in 2007, and scrapped entirely in 2011. But the data that the experiment left behind is pretty staggering.
During the years in which universal screening was employed, there was a large influx of gifted students who were disproportionately likely to be poor, black, Hispanic, or who had parents who didn’t speak English.
Here’s the difference in the cohort immediately before the introduction of universal screening, and the one in the second year of the program:

The changes represent a 180 percent increase in the number of disadvantaged students, an 80 percent increase in the number of black students, and a 130 percent increase in the number of Hispanic students classified as gifted.
The researchers—David Card, an economics professor at the University of California, Berkeley, and Laura Giuliano, an associate professor of economics at the University of Miami—suggest that universal screening leveled the playing field for students who traditionally get overlooked in referral-based systems.
Notably, the study shows that students who might not have been classified as gifted under the old regime did well once they got into the gifted programs. “[I]f anything, the newly-identified students benefitted even more from participating in gifted education than did the group of always takers who [would] be identified under a traditional referral system,” the researchers observed. An “always taker” is the sort of student who likely would have ended up being IQ-tested even in the absence of universal screening.
The previous regime had badly skewed the distribution of gifted children towards richer, whiter geographical areas. Half of gifted students were in schools that served just 18 percent of the population, a proportion that changed dramatically with universal screening.
But the district, facing a budget crunch, eventually stopped universal screening because of the added expense of having so many more students take the tests, which were administered by school psychologists and required a lot of overtime pay. Things quickly went back to the way they had been before the introduction of universal screening.
Given how many gifted children the old regime seemed to miss, and the economic and racial homogeneity it seemed to promote, the overtime seems like it might be worth paying.