On orthogonal designs and regression

This video gives an introduction to the concept of ortogonal designs.
This video was recorded by Dr. Erik Vanhatalo, Quality technology and logistics, Luleå University of Technology (LTU), Sweden. The primary purpose of this video is to be learning material for undergraduate and graduate students following a course in design and analysis of experiments at LTU. The course book used in these courses are primarily: Montgomery, D.C. (2013). Design and Analysis of Experiments. Wiley.

[@dennisowusu8247]

the pressure variables supposed to alternate 40 40 80 80 per the coded variable x2

[@punksnotdead4766]

Just spotted that too. Mistake in the book I think

[@erikvanhatalo7]

Thanks Dennis, good of you to notice that! You are correct in that the pressure variable in the natural units does not match the coded pattern. This image is borrowed from the book companion slides so it is a typo in Montgomery's book. Nonetheless, the mistake was also mine in not noticing that. Best wishes, Erik

[@karnam7444]

Hello Sir, great video, thanks for this! A quick question. How would you regress the higher order term such as A^2, B^2 which are quite common in any response surface design? I researched a lot about this, but couldn't find eneough help.

[@erikvanhatalo7]

Thanks! Glad you liked it. Now in order for you to fit second order terms, such as A^2, without confounding you typically need a second order design. You may want to chck out central composite designs or Box-Behnken designs. These are examples of common designs in response surface methodology. Cheers!