The Wall Street Journal presented a one-sided picture of the charter school network Knowledge Is Power Program, touting a KIPP charter school's higher test scores while ignoring criticism about KIPP schools' selection process and attrition rates.

The Journal, reporting on school closings in Washington, D.C., noted that test scores at a KIPP charter school are higher than at a nearby public school:

Since 2009, the portion of Davis students who tested proficient in reading doubled to 34%, while math proficiency jumped to 35% from 22%. At the nearby KIPP school, 59% are proficient in reading and 75% in math.

But the Journal made no mention of how KIPP has been scrutinized for student selection and for high attrition rates among lower-performing students who are admitted but never graduate.

In March 2011, researchers at Western Michigan University and Columbia University released a report showing that KIPP schools have higher rates of attrition than traditional public schools and enroll fewer students with disabilities and limited English language skills.

According to the report, “KIPP schools enrolled a lower percentage of students with disabilities (5.9%) than did their local school districts (12.1%)” and “enrolled a lower percentage of students classified as English Language Learners (11.5%) than did their local school districts (19.2%).”

The report found that this “selective entry of students” as well as a high rate of attrition among lower-performing students without replacing them are responsible for KIPP's success at improving student performance:

High rate of student attrition with nonreplacement: The departure of low-performing students helps KIPP improve its aggregate results. Unlike local school districts, KIPP is not replacing the students who are leaving. When a student returns to a traditional public school after the autumn head count, KIPP retains most or all of the money (the amount depends on the particular state) allocated for educating that student during that school year. Traditional public schools do no typically benefit in the same way when they experience attrition, since vacancies are typically filled by other mobile students, even in mid-year. The discussion of findings at the end of this paper describe how “peer effects” play to KIPPs advantage, especially given its practice of filling few of the large number of vacancies from students who leave.

The report further stated that KIPP schools have “substantially higher levels of attrition than do their local schools districts.” On average, “approximately 15% of the students disappear from the KIPP grade cohorts each year.” Moreover, 30 percent of KIPP students and 40 percent of African-American male students leave KIPP schools between the sixth and eighth grades. KIPP officials have disputed the report. 

Richard D. Kahlenberg, a senior fellow at The Century Foundation, a progressive non-partisan think tank, echoed the Western Michigan study's findings, writing in a June 2011 blog post: 

KIPP hardly demonstrates that with the right teaching approach, economic segregation matters little in public education, because, just below the surface, KIPP schools are demographically nothing like regular high poverty public schools. By definition, KIPP students are from self-selected families who chose to enter a lottery; and KIPP has very high attrition rates. 

In his book Class and Schools: Using Social, Economic, and Educational Reform to Close the Black-White Achievement Gap, education expert Richard Rothstein argued that KIPP neglects those students most in need, writing: 

They select from the top of the ability distribution those lower-class children with innate intelligence, well-motivated parents, or their own personal drives, and give these children educations they can use to succeed in life.