Question

1.Why/When would you use a screening design?

2. What does an orthogonal design mean?

3.T or F: A 2-factor design is said to be balanced if each factor is run an unequal number of times at the high and low levels.

Answer 1

Solutions:

1. Screening design is used to identify the most important factors that affect quality . After screening experiments , you usually do optimization experiments that provide more details on the relationships among the important factor and response variables.

The following designs are often used for screening:

• 2-level fractional factorial designs
• Plackett - Burman designs
• Definitive screening designs

2. Orthogonality refers to property of design that ensures that all specified parameters may be estimated independent of any other. A complete factorial design is both orthogonal and balanced. Two vectors are orthogonal if the sum of the products of their corresponding elements is 0.The concept of orthogonality is important in Design of Experiments because it says something about independence.  Orthogonality guarantees that the effect of one factor or interaction can be estimated separately from the effect of any other factor or interaction in the model.That's called Orthogonal designs.

3. It is false because a 2-factor design is said to be balanced if each factor is run an equal number of times at high and low levels.