=+14. Experiments often have more than one response value of interest. In the article “Towards Improving the Properties of Plaster Moulds and Castings” (J.

Engr. Manuf., 1991: 265–269), a study was undertaken to determine the effects of carbon fiber (in %)

and sand addition (in %) on two response variables, casting hardness and wet-mold strength.

Sand addition (%)

Carbon fiber addition (%)

Casting hardness Wet-mold strength 0 0 61.0 34.0 0 0 63.0 16.0 15 0 67.0 36.0 15 0 69.0 19.0 30 0 65.0 28.0 30 0 74.0 17.0 0 .25 69.0 49.0 0 .25 69.0 48.0 15 .25 69.0 43.0 15 .25 74.0 29.0 30 .25 74.0 31.0 30 .25 72.0 24.0 0 .50 67.0 55.0 0 .50 69.0 60.0 15 .50 69.0 45.0 15 .50 74.0 43.0 30 .50 74.0 22.0 30 .50 74.0 48.0