Mastermind and Interactions

The board game, Mastermind, can be used to demonstrate interactions and main effects in an abstract way.

Here is Wikipedia's description of Mastermind (click here). Downloadable versions of Mastermind can be found near the bottom of that page. Finding original games is still possible. Try an eBay search for Mastermind, for instance.

Playing Mastermind is, ultimately, a search for the interaction of its two variables (a.k.a. main effects) peg color and peg position. A player wins when the opponent's pattern of pegs has been decoded. During play, the coding player provides feedback (or, values for a dependent variable) using white or black pegs. A white peg indicates that the correct color of a peg has been decoded, but that the peg is not in the correct position. A black peg indicates that both the color of the peg and its position are correct. The decoding player wins when all of the feedback pegs are black.

Mastermind can also be used to illustrate (again, in an abstract way) effective experimental design. Decoding players who do not plan their decoding stategy will nearly always fail to discover the coded pattern. Try a game or two.