But these investments are complicated and require a great deal of attention, even from the professionals who trade in them.

But an investment still requires deep pockets and plenty of land.

It is often observed that successful investment requires each investor in a financial market to guess what other investors will do.

The difficulty is that these investments will be costly, and may require an increasing share of each nation's gross domestic product.

The next major investment is scheduled for 1996, when the first of the system's 24 cars will be 50 years old and will require replacement.

Private investment, in sum, requires an adequate infrastructure, many economists contend.

As such, planning also provides the predictability that future private investment requires.

Question marks must be analyzed carefully in order to determine whether they are worth the investment required to grow market share.

Some investments require patience before they offer a return.

A common market and competition in it, and above all effective investment, require good, comparable statistical data.