Four surgical centers formed a collaboration to reduce post-operative infection rates.

Detailed Explanation:

To meet the goal, each center must reduce infection rates by at least 20% from their baseline:

Center D:

Baseline = 4.7%, Outcome = 3.7%

Reduction =

(

4.7

−

3.7

)

/

4.7

=

21.3

%

(4.7−3.7)/4.7=21.3%, meeting the 20% reduction target.

Other Centers:

Centers A and B did not show a 20% reduction; Center C reduced from 5.2% to 4.3%, which is only around 17.3%.