funnel of doubt

The shape of a graph to illustrate a range of probable outcomes from a given investment strategy. If the desired outcome is represented by a straight line half way up the vertical axis (investment return) and parallel to the horizontal axis (time), the range of probable outcomes around the centre near the vertical is very small but it widens with the passage of time, making a funnel.

Some investment strategies (eg 100% UK Government bonds and gilts) will have a very narrow funnel representing a narrow range of probable outcomes while other, more volatile strategies, will result in a much wider range (ie a much wider funnel).