(FORTUNE Magazine) – ''Quick -- what's the gross national product?'' That grabby interrogatory, which we incidentally recommend as a guaranteed conversation starter in awkward social situations, was the first sentence to appear in the Keeping Up column. It was composed for the December 1976 issue of this publication (then a monthly), meaning that the column is now celebrating its tenth (tin or aluminum) anniversary. Several colleagues who possibly mean well have jovially suggested that an inspiring way of memorializing the great event would be for the present keyboarder to produce a column owning up to all the mistakes of fact, judgment, and fairness committed under his byline during the decade. An unstated premise of the suggestion was that the mistakes would fill a whole column. Well, we shall see. But first, the GNP. The somewhat aggrieved thought behind that first item was that nobody paid attention to nominal GNP anymore. All the discussion was about the percentage change from one period to the next and about how it was divided between real growth and inflation. Even learned economists, Keeping Up lamented, could no longer tell you off the tops of their heads the actual dollar value of the goods and services being produced annually in the country. (It was then $1,710 billion and is now $4,234 billion.) Just why we were feeling so exercised about this situation is admittedly not too clear from today's vantage point, and doubtless some wisenheimers down the corridor will argue that we started out with a judgmental error right there in the very first sentence. For the time being, however, we are counting only the following transgressions: It hurts to say so, but in the course of otherwise validly arguing that insider trading does more good than harm, we got carried away in claiming (July 21, 1986) that insiders who trade do not necessarily reduce the profits of the outsiders. Obviously -- at least, it is now obvious -- they must reduce outsider profits. When a stock with one million shares rises from x dollars to y dollars a share, the total gains to investors are a finite amount: one million multiplied by (y dollars minus x dollars). If insiders are taking part of that amount, then less is left for outsiders. We have a particularly maddening problem about Paul Samuelson, Nobel laureate and author of the famous textbook Economics. A while back (April 2, 1984), yours truly got to arguing with Paul about gambling. We ungently chided him for not seeing that gambling has entertainment value and, therefore, utility. Next we proceeded to expound our one prideful contribution to economic theory, which is that gambling is conceptually indistinguishable from saving. The idea is that you can convert a stream of income into a lump of capital by certain traditional forms of saving -- by putting aside a little of the income every week, say -- or you can achieve the same result by making a series of long- shot bets. Ultimately, you will win one of the bets, and at that point you will have a lump of capital, just like the folks in Christmas Clubs. Brilliant, eh? About a year later, we were browsing through the 11th (1980) edition of Economics and somehow landed on a footnote not previously noticed. It was doubly dismaying. First, the footnote made clear that Samuelson does in fact acknowledge gambling to be recreational. Worse, it made clear that our contribution to economic theory was less original than postulated. Said the footnote: ''Oddly, some people who do not trust their ability to save do use the steady purchase of lottery tickets as a way . . . of occasionally accumulating larger sums of money.'' Our otherwise incisive commentary on the desirability of living in Pittsburgh (May 13, 1985) was marred by a logical lapse. The Steel City, you may recall, had been judged by Rand McNally to be the best place to live in the whole U.S. However, this judgment rested on a weird computation. Every one of the 329 metropolitan areas in the country was ranked by nine criteria (housing ; costs, climate, etc.), and Pittsburgh came in first because its average score was best. What made the computation weird, or at least arbitrary, was Rand McNally's assumption that all the criteria were of equal weight. We pointed out that if you doubled the weight given to climate, then San Francisco would have been first (and Pittsburgh fifth). Which was okay up to that point. But then we got carried away again, fallaciously arguing that the results would have been quite different from Rand McNally's if you used your computer to assign random weights to the different criteria. Months later, a mathematical friend unkindly pointed out that in the long run, random weights would kick out the same results as equal weights. We were basically right in arguing (November 10, 1986) that laws banning age discrimination overlook the decline in mental ability among old folks. However, the ''cross-sectional'' data we used as evidence of decline were probably misleading. The data, lifted from Wechsler's Measurement and Appraisal of Adult Intelligence, by Joseph D. Matarazzo of the University of Oregon Medical School, compared the test scores of different people of different ages and showed substantial declines with age beginning as early as the late 20s. A better way to track the effect of age is to do a ''longitudinal'' study -- that is, to follow the same people over time. Matarazzo's work also includes longitudinal data, and we should have cited them. In general, they show test scores to be stable or even rising until around 50. The ensuing declines are moderate until around 60, after which they appear fairly severe. Absolutely nobody has pointed this out, but we worry that Keeping Up has an emerging logical problem in the area of corporate social responsibility. Along with Milton Friedman, whom we have occasionally (e.g., February 23, 1981) quoted on the subject, we keep arguing that businessmen have no special competence in solving social problems and no right to invest their stockholders' money in attempted solutions; accordingly, they do best when they just keep their minds on maximizing returns. But Keeping Up hasn't exactly been consistent. Occasionally, it has even sounded as though it believes business should defend the national interest. We have assailed executives like Walter Wriston for doing capitalist deals with the Communists in Eastern Europe (February 22, 1982) and also suggested that it was irresponsible for American companies to be dealing with Marxist Angola ) (November 25, 1985). It would be more sensible to stop blaming businessmen for dealing with Communists and start demanding that Congress restrict such investment, as it has in South Africa. Meanwhile, we will feel free to stick it to Gulf Oil (now part of Chevron) for lobbying in favor of the infamous Clark Amendment (which in effect banned American aid to the anti-Communist rebels in Angola for many years).

That's about as far as we stretch, fellows.