Now Playing: Tests for Two Proportions (3:59)

I adore NCSS and PASS. I have been using them for 20 years now.

Mario Martinez Gonzalez, MPH, FEE, MD, Universidad Nacional Autonoma de Mexico

"PASS 13 is fantastic! Better than my new dishwasher and microwave combined."

Dr. Barbara Tabachnick, CSUN, Author