If Hanukkah celebrations are indeed a bulwark against Christian religious imperialism, then the most active observers of the "Jewish Christmas" should be those who are vulnerable. The authors of the study (parents all of them) hypothesize that children are most susceptible to Christmas envy, and, indeed, households with children were half as likely to skip Hanukkah candle-lighting as households with no children.
Of course, it's possible that people with kids may use just about anything as an excuse to have a party—birthdays, Valentine's Day, Halloween. So the authors compare Hanukkah with Passover, the springtime festival when Jewish parents face more modest competition from the Easter Bunny. It turns out that having children has no effect on the likelihood of attending a Seder, the traditional meal eaten on the first two nights of Passover. So it seems it is competition from Christmas, not just the presence of children, that makes families more likely to celebrate Hanukkah. (The authors parse the data in a number of other ways to further validate their Christmas hypothesis.)
The researchers also analyze the holiday money trail, using county-by-county data on "Jewish Products" expenditures made at a large supermarket chain. In counties where Jews are more outnumbered by Christians—and hence exposed to greater Christmas spending pressures—there is a bigger jump in purchases of Jewish products in December compared with more-Jewish areas, presumably as a result of increased sales of candles, latkes, and other Hanukkah paraphernalia. Jewish expenditures also spike during springtime Passover celebrations, when Jewish shoppers stock up on matzo and kosher wine. But the percentage increase in sales isn't any bigger in Christian-dominated counties than in less Christian counties, again suggesting that Hanukkah celebration correlates with competition from Christmas.
Adam Smith thought of competition—religious or otherwise—as mostly a good thing, and most economists would agree. But one wonders what Smith would make of the Hanukkah boom in America today. Rather than rabbis and synagogues providing better services, a minor holiday largely unrelated to Judaism's core values has earned outsize importance, primarily so parents can bribe their kids into keeping the faith. However, if recent retail numbers are any indication, the current economic climate may put the brakes on some of this year's Christmas extravagance, thereby giving a reprieve to parents of all religious persuasions. Perhaps this will provide an opening to less consumerist approaches to competing for holiday cheer and remind economists that, despite their arguments to the contrary, the spirit of the holidays isn't only about dollars and cents.