Factors and Responses

[DOENewbie]

I am trying to find the factors and responses in the following statement but am having some trouble deciphering it:

"You wish to investigate the corrosion rate of copper. You want to test hard and soft tempered copper in two different alloys for exposure to the following natural gas contaminants: H2S, Mercaptan, O2, and CO2."

I was thinking that there might be 8 factors, the gases and the temper and alloys but I am not quite sure. I was also thinking that the response was the corrosion rate of copper.

Thanks

[JohnM]

Yes, the response is corrosion rate.

There are 3 factors:

temper (hard, soft)
alloy (1, 2)
gas contaminant (H2S, Merc, O2, CO2)

In a full factorial design, there would be 2 x 2 x 4 = 16 treatment combinations.

[DOENewbie]

Great thanks, makes much more sense now, I was only thinking of 2 factor levels. Just curious, I know that with 3 factor levels the coded levels are -1,0,1 but how would you start the set up of four factor levels in a coded table?

[JohnM]

Never really bothered with coding issues, but this page shows dummy and effect coding for a 4-level factor:

http://www.gseis.ucla.edu/courses/ed...s1/orthog.html