There's no easy answer. But if you have the stomach for it, the answer might be yes.

Q: I'm a heavy radio advertiser, currently reaching 32 percent of my area's 18- to 34-year-old population with a frequency of 2.9 each week, 52 weeks in a row. How much will my store traffic increase if I increase my schedule to reach 48 percent of the population with similar weekly frequency? How many more sales will I make?

A: Your question is far more complex than you realize, but I will do my best to answer it. All things being equal, increasing your reach from 32 percent to 48 percent (an increase of exactly 50 percent) should increase your radio-driven traffic by exactly 50 percent. Now for the problems:

1. All things are never equal. My answer assumes there will be no change in the number of competitors in your marketplace or in the attractiveness or aggressiveness of existing competitors--yet rarely do these remain static. If your competitors drop the ball, you may experience a significant increase in traffic without increasing your ad budget at all. Likewise, if your "share of voice" increase is matched by similar increases from your competitors, yours will be effectively nullified and store traffic will remain at current levels. But what if they increase their ad spending and you don't increase yours? You want to do the math on that one?

2. What percentage of your traffic is currently radio-driven? What percentage is location-driven? What percentage are repeat customers? What percentage are referrals? Yes, a 50 percent increase in reach (without a decline in frequency) should increase your radio-driven traffic by 50 percent. But can you tell me how much of your traffic is currently due to your advertising alone and is coming for no other reason?

Are you beginning to understand why it would be completely irresponsible of me to predict the bottom-line impact of an increase in advertising? But this is my day to be irresponsible, so here's my best attempt at an answer: My instinct is that 50 to 70 percent of the typical retailer's store traffic is due to location, signage, repeat customers, referrals and so on, and the remaining 30 to 50 percent of store traffic is advertising-driven. This would mean that a 50 percent increase in effective reach should increase traffic by 15 to 25 percent.

To summarize what I said earlier, advertising-driven traffic should increase by the same percentage that you increase your effective reach, all other factors remaining equal. Now if you can just plug in the exact number of selling opportunities that your stores have each day as a direct result of advertising alone, then-presto--you'll have your answer.

Bottom line: Every business owner must decide for themselves what percentage of their profits to take out of their company and how much to reinvest in their facilities, equipment, advertising and people. Sadly, due to the near-universal fear that "if it doesn't work, I've wasted my money," very few entrepreneurs are willing to advertise as aggressively as they should. Consequently, I would like to see you go to the next level--if you can afford the dollars--and stomach the risk.

A closing thought: There's only one thing that business owners are more reluctant to spend profits on than advertising, and that's training their people. Their eternal question is, What happens if I train them and they leave? But here's a better one: What happens if you don't train them and they stay?

Nicknamed "the Wizard of Ads" by an early client, Roy H. Williams and his staff have often been the unseen, pivotal force in amazing come-from-behind victories in the worlds of business, politics, and finance. Williams is the author of The Wizard of Ads, Secret Formulas of the Wizard of Ads, Magical Worlds of the Wizard of Ads, Accidental Magicand Free the Beagle.

The opinions expressed in this column are those of the author, not of Entrepreneur.com. All answers are intended to be general in nature, without regard to specific geographical areas or circumstances, and should only be relied upon after consulting an appropriate expert, such as an attorney or accountant.

##### Roy H. Williams

Roy Williams is the founder and president of international ad agency Wizard of Ads. Roy is also the author of numerous books on improving your advertising efforts, including The Wizard of Ads and Secret Formulas of the Wizard of Ads.