According to an investigation by The Atlanta Journal-Constitution, the Dallas Independent School District and 16 other North Texas districts exhibit suspicious test scores that point to the possibility of cheating on standardized testing.
The newspaper examined test results for 70,000 public schools across the country and found high concentrations of suspicious scores in school systems.
The Journal-Constitution said its analysis does not prove cheating. It reveals that scores in roughly 200 districts followed a pattern that indicated cheating in multiple Atlanta schools.
However, the Texas Education Agency said it does not plan to investigate the test scores, saying it questions the newspaper's methodology. Agency spokeswoman Debbie Ratcliffe said the newspaper tracked scores by school, not by student. She said that could affect results by 20 percent.
The Journal-Constitution reported in 2008 and 2009 about statistically improbable jumps in test scores within the 109-school Atlanta Public Schools system. Those reports led to an investigation by Georgia officials, which found that at least 180 principals, teachers and other staff took part in widespread test-tampering in the 50,000-student district.
In Sunday's editions, The Journal-Constitution reported that 196 of the nation's 3,125 largest school districts had enough suspect test results that the odds of the results occurring naturally were less than one in 1,000.
For 33 districts nationwide, the odds of their test scores occurring naturally were worse than one in a million.
In nine districts -- Atlanta; Baltimore; Dallas; Detroit; East St. Louis, Ill.; Gary, Ind.; Houston; Los Angeles; and Mobile County, Ala. -- scores careened so unpredictably that the odds of such dramatic shifts occurring without an intervention such as tampering were virtually zero, the newspaper found.
The Journal-Constitution analysis found 17 North Texas districts with a 5 percent or greater test score irregularity: Wylie, Weatherford, Waxahachie, Rockwall, Midlothian, McKinney, Lewisville, Lancaster, Keller, Irving, Frisco, Duncanville, Dallas, DeSoto, Crowley, Coppell and Allen.
The North Texas district with the highest percentage flagged in the study was Duncanville Independent School District with 23.3 percent. The largest district tagged was Dallas, with 10.76 percent.
In Houston, test results for entire grades of students jumped two, three or more times the amount expected in one year, the analysis showed. When children moved to a new grade the next year, their scores plummeted -- a finding that suggests the gains were not because of learning.
"These findings are concerning," U.S. Secretary of Education Arne Duncan said in a statement after being briefed on the Journal-Constitution analysis.
He added that "states, districts, schools and testing companies should have sensible safeguards in place to ensure tests accurately reflect student learning."
However, DISD spokesman Jon Dahlander told NBC 5 that the Texas Education Agency pointed out that the newspaper's analysis did not track students from year to year.
"Although there may be 50 students in year one and 50 students in year one, there is no reason to believe these are the same students," the agency said.
The TEA said the Journal-Constitution's analysis had several limitations.
The newspaper's method did not account for false positives, did not make adjustments to account for small campus sizes and did not take into account student data. The analysis also flagged schools that were underperforming, which "does not necessarily make sense in the context of a cheating investigation," the TEA said.
Ratcliffe said that TEA authorities had contacted districts that were implicated in the Journal-Constitution story to ensure they were analyzing necessary data and talking to school principals. Uncovering wrongdoing is up to individual school districts, she said.
NBC 5's Lindsay Wilcox and Greg Janda contributed to this report.