An analysis of 225 terrorism cases inside the United States since the Sept. 11, 2001, attacks has concluded that the bulk collection of phone records by the National Security Agency “has had no discernible impact on preventing acts of terrorism.”

In the majority of cases, traditional law enforcement and investigative methods provided the tip or evidence to initiate the case, according to the study by the New America Foundation, a Washington-based nonprofit group.

The study, to be released Monday, corroborates the findings of a White House-appointed review group, which said last month that the NSA counterterrorism program “was not essential to preventing attacks” and that much of the evidence it did turn up “could readily have been obtained in a timely manner using conventional [court] orders.”

Under the program, the NSA amasses the metadata — records of phone numbers dialed and call lengths and times — of virtually every American. Analysts may search the data only with reasonable suspicion that a number is linked to a terrorist group. The content of calls is not collected.