More than 7,000 students were incorrectly graded on the standardized test required for admission to most New York City private schools, the test company confirmed on Friday.

Parents were notified of the error Thursday night, two days after new scores were reported to schools — and several weeks after final decisions were made about admissions.

Parents of the students affected received notification of the error and the revised scores for the Independent School Entrance Exam in letters sent by same-day service from the Educational Records Bureau, known as the E.R.B., which administers the exam. In the letters, officials from the E.R.B. played down the importance of the test scores, saying they were just one of many components of applications that might include grade point average, essays and teacher recommendations.

It would be hard to determine how much the incorrect scores affected individual children or the group in terms of admissions. And now that most students have decided which school they will be attending, the re-issued scores are unlikely to have much impact.