Test Page Counts to Determine Online Impact

Dear Dr. pROfIt: We’re having an argument at work about page counts in our catalog. We currently mail a 96-page monthly catalog, and our vice president wants to reduce the page count to just 64 pages a month. I'm worried that if we do that, we'll lose sales over the phone and online. Currently, 70 percent of our catalog sales happen online. How do I convince our vice president to keep mailing 96-page catalogs?