This week's rude question: How many McJobs   does it take to produce a Social Security retirement check?

If we treated this as a light bulb joke--- as in "How many BLANK does it take to change a light bulb?"--- We could expect a variety of answers, such as:

•  No one knows for certain, but the number is rising.

•  Three, at last count, plus a crowd of anxious watchers.

•  Four, if one of them is blonde.

To avoid a lot of confusion and bad jokes, allow me to introduce the McJobs/Retiree Exchange Rate, complete with a supporting on-line calculator.   It measures how many workers it takes to pay in enough employment tax revenue for a retiree to receive his or her particular monthly check. (You can access the calculator at www.scottburns.com. There is no charge but registration is required.) Unlike the usual reporting on Social Security--- including mine--- this is a very personal measure.   It uses monthly retirement checks that are under $2,000 and hourly wages that are under $44.   No billions or trillions need apply.

That way, a retiree can get a very direct measure of who is supporting her-- and how many of them it takes.

I've called it the McJobs/Retiree Exchange Rate because the word McJobs, has come to symbolize the job future many young workers fear--- a long series of unrelated jobs with low pay and minimal benefits. I mean no disrespect for McDonald's, which has trademarked the word "McJOB,"only recognition that the phrase and company have top dog 'share of mind' when it comes to public discussion of jobs.

So let's get to it.

According to the Social Security Administration, the average retirement check in August was $926.90. The largest possible check for retiring this year at full retirement age is $1,793.61. If we put the minimum wage, $5.15 an hour, in the calculator we learn each hour produces 64 cents of employment tax using the full 12.4 percent employer/employee rate. (Another 2.90 percent goes to Medicare.)

That, in turn, means it takes 1,451 hours of minimum wage work to produce the average retirement check. That's about 9 full-time workers--- a lot of workers. Since the actual ratio of workers to retirees is currently about 3-to-1, we're fortunate that many workers earn a good deal more than the minimum wage.

The average worker at Wal-Mart, for instance, is reported to earn about $9.70 an hour with minimal benefits. That means a Wal-Mart worker generates $1.20 an hour in employment taxes and would need to work about 770 hours a month to produce that $926.90 check. So it would take nearly 5 full-time Wal-Mart employees to produce one average Social Security check.

With national average hourly earnings at $15.30, the average worker generates $1.90 an hour in employment taxes. The worker would need to work 489 hours a month to generate the average retirement check. That's roughly equal to 3 full time workers.

Now let's try the other end of the wage scale.

For 2004 the top of the employment tax wage base is $87,900, an income that figures to about $44 an hour. Only about 7 percent of all workers earn more.   Those at the top pay about $5.46 an hour in employment taxes--- more than the minimum wage.   It takes only one top earner to make good on the average retirees' Social Security check.

Why am I telling you all this?

Simple. As the boomers head toward retirement, we need to be keenly aware of the trend in wages. If we create too many McJobs and not enough Big Jobs, or if Big Jobs are displaced by McJobs, paying out those retirement checks will get pretty iffy. If you are retired or about to retire, you should start to think up-close-and-personal about your real life "support group"--- the team of workers that pays your bills.

On the web:

The origins of "McJobs": http://www.theregister.co.uk/2003/11/11/merriamwebster_explains_disappearing_mcjob/

Average Social Security benefits 1940-2002: http://www.infoplease.com/ipa/A0780010.html

Average monthly Social Security benefit for a retired worker, August, 2004: http://www.ssa.gov/policy/docs/quickfacts/stat_snapshot/index.html#table2

Table of monthly benefits by age: http://www.ssa.gov/OACT/COLA/examplemax.html

The McJobs/Retiree Online Calculator: www.scottburns.com