Using Variable Ratio/Variable Reward to encourage saving

I just read this interesting piece by Jason Zweig about a bank that is offering prizes (or raffles) just for opening a bank account.

We all know that variable ratio / variable reward is the best way to encourage behaviors. Think of gambling (don't know when you're going to win or how much you're going to win) or even other activities such as golf (don't know when the next good shot will come or how great it will be).

Of course, the rates are a little lower than current market and the differential is how the credit union pays for the "prizes." The article reports the following: "You are sort of betting, but there's no losing."

But in reality, there is losing because of the differential in return and losses to inflation. How you make it up is in the risk/reward ratio. If you contribute the minimum like the reported person who placed only $25 in their CD (Certificate of Deposit) and won $400, the ratio is more justified as compared with someone who opens their CD with $100,000 and wins $400, but misses out in $1,000 for every 1 percent interest rate differential.