It's initially all about numbers- GPA, BCP GPA, DAT. If you look at the AADSAS website describing applicant reports available to schools this should be obvious. A high GPA, good DAT, volunteer time, shadow time, and whatever else will make a strong app. A W or I on the transcript shouldn't matter. A W or I on the transcript every semester might. Several Ws or Is on the transcript in one semester might matter. If all you have is one W or I, I wouldn't worry about it - if your app is strong overall.