A spokeswoman for the company, Susan Rosenberg, said the information is proprietary.
But when sponsors ask about the profits their plans generate, they are typically told the information is proprietary.
But the plan may not be as detailed as some local officials would like because much of that information is proprietary to Aventis, Dr. Cohen said.
The data is lacking, Dr. Bell said, because "in agriculture, industry has been reluctant to provide it, saying the information is proprietary".
In the United States, some drilling companies have been reluctant to reveal the chemicals they use in fracking, saying the information is proprietary.
Ms. Miller-Kovach said she could not divulge the number of fruits and vegetables used in the calculation because the information is proprietary and not revealed even to participants.
"Some of that information is proprietary," says Fletcher.
Prudential declined to answer, saying that information was proprietary, he said.
He declined to say how many were sent or whether they were all missing the voter registration numbers, saying the information was "proprietary".
A spokeswoman for Golden Rule declined to explain how long it had been excluding Caesareans, how it had decided to do so or how many were affected, saying the information was proprietary.
