Numbers don't tell the whole story with some growth stocks -- sometimes you have to look at what the company does.

Erik Voss, portfolio manager of Seligman Growth,says he and his team of analysts pick stocks each week that are going to rise steadily or that will break out because of some outside event.

Finding those stocks involves studying the bigger trends and meeting with management. It means talking to suppliers and competitors to build a picture of the company.

A stock has to get past Seligman's team of analysts. Voss also seeks other experts who know the company or industry. Outside experts often can verify a company's fundamentals, as well as offer useful perspectives. For instance, for a health care stock he might ask a doctor who uses its products.

If a stock passes muster with both groups, then it gets into the fund.

Voss says he isn't ignoring quantitative measures of a stock's health. But he doesn't put as much weight on them as many other managers might.

He bought Transocean in the first quarter, when it was trading at about 120 to 130. The stock now trades near 145 and has an IBD Composite Rating of 99. The oil rig provider was among the fund's 10 biggest holdings on March 31.

Voss says that profits look good out to 2010 at least, and probably longer. "I'm a long-term energy bull," he says. "For the first time, Transocean has signed contracts that lock up their work for five years."

Transocean's growth is also less tied to whether new oil supplies are found. The company's profits are made extracting the crude. If that becomes more difficult, then Transocean profits. "We've found all the easy oil," Voss said.

New supplies of oil won't change the fact that demand is rising, he adds.

Building The Grid

It isn't just oil he's interested in. Other kinds of infrastructure will need to be built. Voss says that in the U.S. a lot of money will need to be put into upgrading the electricity grid.

Electrical parts maker ABB took up about 2% of fund assets as of March 31.

Two to three years is the usual holding period, Voss says. Turnover runs at about 180% per year.

If a stock gets to his price target much faster than that he'll take another look to see if there was some catalyst behind the move. If it's something sustainable he will stay in the position.

Most investments start at about 1%. Positions of 3% to 5% are the largest holdings. And occasionally if a stock is on a run, Voss will let it get to 7% of assets, but that is rare.

The fund is usually fully invested, though it now has about 3% in cash.

Marvell Technology Group was among the top 10.

The company makes application processing chips for Research In Motion (NasdaqGS:RIMM - News). Voss says he bought Marvell at about 10.50 in March. It now trades near 15.

Originally the company had problems because it signed a contract with Intel (NasdaqGS:INTC - News) to buy chips. Voss says the price they paid was above-market, hurting the balance sheet, as well as the stock.

But as that contract has expired Marvell is now free to seek cheaper suppliers. The chips bought from Intel are being sold off.

That means the cost structure of the business is improving. Among recent big sells were diesel engine maker Cummins and Boeing.

Diesel demand has risen somewhat because of tougher mileage standards and high gas prices. Diesel is also a common fuel in Europe. But a slowing economy will likely crimp sales.

Voss sold Cummins in the 50 range, after holding it for about nine months to a year. By Jan. 22, it was 46% off its October high. The stock has since gone on to a new high.

Boeing is similar. Though it makes more efficient airplanes than before, Voss sees demand slowing.