12.18. An experiment was run in a wave soldering process.

There are five controllable variables and three noise variables.

The response variable is the number of solder defects per million opportunities. The experimental design employed was the following crossed array.

(a) What types of designs were used for the inner and outer arrays? What are the alias relationships in these designs?

(b) Develop models for the mean and variance of solder defects. What set of operating conditions would you recommend?

Outer Array F -1 1 1 Inner Array G -1 1 -1 1 A BCDEH-1-11 1 1 1 1 -1 -1 194 197 193 275 1 1 1 1 136 136 132 136 1 1 185 261 264 264 264 -1 47 125 127 42 -1 1 1 1 -1 295 216 204 293 -1 1 -1 -1 1 234 159 159 231 157 -1 -1 1 1 1 328 326 247 322 -1 -1 -1 -1 186 187 187 105 104