In an 18-year research project, Phillips studied the mortality rates of nearly 2,000 Californian Jews.
He found that the death rate dipped 35 percent below normal in the week before Passover and peaked by an equal percentage above normal in the week following the holiday. The study was published in the Lancet, a prestigious British medical journal.
"It is my hypothesis that those nearing death may feel that an extended family gathering at Passover offers the chance of saying hello and goodbye for the last time," says Phillips.
The sociologist, an observant Jew and a native of South Africa, says he cannot pinpoint the social, physiological or biological factors that might be at play in the "Passover Effect." But he has little doubt that some form of psychological process is involved.
The Passover findings were similar to those in an earlier statistical study by Phillips that focused on Yom Kippur and used records of Jewish deaths in New York and Budapest at the turn of the century.
Popular belief has long held that people can postpone dying — either through willpower or religious faith, Phillips observes.
"It is not uncommon for people to bargain with God for an extension of life until a significant occasion has arrived," he says.
A historical example of such "bargaining" is cited in the deaths of Presidents Thomas Jefferson and John Adams. Both men died on July 4, 1826. Friends and relatives of the two founding fathers said they had wanted to live until the 50th anniversary of the signing of the Declaration of Independence.