EDITORIAL If Mayor Gavin Newsom is serious about stimulating the San Francisco economy, he ought to start with a basic number that the city's own economist, Ted Egan, passed along to us this week. The number is 2.11 — and Egan says that's the multiplier effect of cuts in local public spending.

In other words, every dollar Newsom cuts from the city budget has a ripple effect of taking $2.11 out of the San Francisco economy. Which means that if the mayor decides to solve the city's $520 million deficit with cuts alone, he'll be taking more than $1 billion out of the local gross domestic product.

And that, in a nutshell, is the problem with the mayor's economic stimulus package: it's entirely aimed at the private sector, with no regard for how it will hit public spending.

A dose of reality here — public-sector jobs are also jobs. People who work in the public sector pay rent and mortgages and buy clothes and food for their kids and go shopping in local stores and go to local clubs and restaurants and pay taxes — and have the same economic impacts on the economy as private-sector workers. If you lay off nurses and recreation directors, those people stop spending money in town, and you continue the vicious cycle that has made this recession so deep and painful.

And if your entire economic stimulus program is aimed at cutting private sector taxes, it's going to lead to public sector job losses. And those losses will undermine much of the impact of any gains you might get from private sector job growth.

Egan predicts that Newsom's program of eliminating the payroll tax for new hires would create 4,330 new jobs in the city. We find that something of a stretch — it's hard to imagine how any struggling small business would find eliminating a small tax enough reason to hire a new worker, and small businesses provide the vast majority of the private-sector jobs in San Francisco. But even if it's accurate, it's a fairly tiny gain. The city's lost more than 35,000 jobs since 2007, and when the economy rebounds in the next two years, Egan predicts about 20,000 new jobs in the city even without the stimulus.

Egan also acknowledged to us last year that "the consensus among economists is that most of the time government spending stimulates the economy more" [than tax cuts]."

That's particularly true in a city where the largest employers are all in the public sector (see opinion piece this page).

If the mayor and the supervisors actually want to create jobs in San Francisco, there are plenty of things they can do — starting with finding ways to close as much of the budget gap as possible without layoffs. Here are some possible approaches.

• Put a major revenue measure on the November ballot that saves city jobs without costing private sector jobs. There are several ways to do this, but all of them start with the well-demonstrated concept that transferring wealth from the rich to the poor and middle-class — that is, giving money to people most likely to spend it — is good for job creation. One option: shift the payroll tax to a gross receipts tax and charge bigger companies a higher rate. Another: a commuter tax on income earned above $50,000 a year would charge wealthier people who use city services and don't pay for them.