Dallas Cowboys quarterback Troy Aikman (8) grabs his helmet after being chased out of bounds by Washington Redskins Champ Bailey (not pictured) in the first quarter at Texas Stadium in Irving, Texas, Dec. 10, 2000. Aikman did not return to the game and was diagnosed with a concussion. Reuters

UPDATE: 2:55 p.m. EDT — Following a statement from the NFL that pushed back against a New York Times article Thursday, the paper posted a series of tweets responding to the league's claims. The tweets from the Times defended its story, which reported the NFL used flawed data in a series of studies and connected the league with officials within “Big Tobacco.”

Embedded below is the series of eight tweets:

UPDATE: 12:55 p.m. EDT — The NFL released a lengthy statement in response to a New York Times report Thursday that claimed the NFL used flawed data in concussion studies and tied the league to “Big Tobacco.” The league denied it employed strategies used by the tobacco industry and said that the studies based on a reportedly incomplete data set “were necessarily preliminary and acknowledged that much more research was needed.”

“Today’s New York Times story on the National Football League is contradicted by clear facts that refute both the thesis of the story and each of its allegation,” the NFL wrote.

After saying that the studies mentioned by the Times were not used by the league's current head, neck and spine committee, the statement from the league went on to describe what it felt were the facts of the story. It claimed the studies referenced in the Times story had made clear there were limitations.

“The studies never claimed to be based on every concussion that was reported or that occurred,” the statement read. “Moreover, the fact that not all concussions were reported is consistent with the fact that reporting was strongly encouraged by the League but not mandated, as documents provided to the Times showed.”

The NFL also downplayed connections with those who had been involved with the tobacco industry and denied that the league borrowed its strategy from “Big Tobacco.” The full NFL statement can be read here, and NFL spokesman Brian McCarthy noted on Twitter there would be a further response to the Times' article.

Original story:

The NFL used flawed data in a series of studies that downplayed the potential danger of concussions, and aligned itself with people tied to “Big Tobacco,” the New York Times reported, looking into the 1996-2001 data. Meanwhile, another report this week said since 2008, the league’s PAC has contributed hundreds of thousands of dollars to members of a congressional committee charged with reviewing concussion research.

The Times reported Wednesday, the league’s past concussion research, which was sparked by a slew of concussion-related retirements in the 1990s, was incomplete. The NFL’s research stated it had tracked all team-diagnosed concussions from 1996 through 2001, but the Times reported more than 100 diagnosed concussions were not included in the studies the NFL produced. Among the omitted injuries were high-profile cases involving Dallas Cowboys quarterback Troy Aikman and San Francisco 49er quarterback Steve Young.

The Times also reported by using the flawed data, the NFL’s committee on concussions produced papers that made head injuries seems less frequent than they actually were. The studies have certainly come into question before — especially considering research connecting head trauma suffered by football players and the degenerative brain disease called chronic traumatic encephalopathy — but the underlying data had not been questioned. The Times reported at least 10 percent of head injuries diagnosed by team doctors were missing.

League officials told the paper the clubs “were not required to submit their data and not every club did,” which should have been made clear, but the absent cases were not part of an attempt “to alter or suppress the rate of concussions.”

The full New York Times report also goes into detail connecting the NFL with the much-maligned tobacco industry, including the league’s hiring of a former tobacco-trade-group lawyer to provide legal oversight for the concussion committee. The NFL said there was no connection between the two industries. The Times wrote: “Still, the records show that the two businesses shared lobbyists, lawyers and consultants. Personal correspondence underscored their friendships, including dinner invitations and a request for lobbying advice.”

Meanwhile, the San Jose Mercury News reported Wednesday on a more recent concussion issue for the NFL. Using analysis from the nonprofit MapLight, the paper reported the NFL’s Gridiron PAC had contributed nearly $300,000 to 41 of the 54 members of a congressional committee reviewing concussion research.

The U.S. House Energy and Commerce Committee began informal hearings last week on the issue. The Mercury News reported the NFL’s political action committee has spent 17 percent of its contributions, totaling $292,000, supporting energy and commerce committee members since 2008. The PAC gave $25,000 to Michigan Republican Fred Upton, the committee chair.

At an energy and commerce committee roundtable last week, Jeff Miller, the NFL’s senior vice president for health and safety, said there was “certainly” a connection between head trauma and CTE. It was the first such definitive statement from a league official.

Closing the league’s owners meetings Wednesday in Boca Raton, Florida, NFL commissioner Roger Goodell said that a potential connection between CTE and football is “consistent with our position over the years.”