A Scatterplot or Scattergram searches for a relationship netween two variables; the varibles can be related to causes or effects. Data is gathered in pairs–the first plotted on the X-axis and the second on the Y-axis. Then the intersection of the two is marked by making a dot. In enumerative statistics, this is known as correlation and is actually assigned a coefficient of strength of relationship (not causation).
A Scatterplot can be constructed in MS Excel by using: Insert » All Chart Types » Scatter.
An example from SPC for Excel: