Two techniques for producing a certain part are available. To compare them, each method produces 200 parts, and the numbers of defects for them are observed. Method 1 had 15 defects, and Method 2 had 27 defects.
(a) What is the sample difference between the proportions of defects for these two methods? What is the standard error for this difference?
(b) If these 400 parts represent a large population of parts to be produced, estimate the difference between the proportions of defects in this population. Use 99% confidence.
(c) Based on your answer in part