Hi Karen,
To get the count of students who have completed all the tests:
Code:
=COUNTIFS(B2:B100,"<>",D2:D100,"Yes",E2:E100,"Yes",F2:F100,"Yes")
Let's say you put that formula in cell H2. Then, to get the count of students who have not completed all three tests you could use this formula:
Code:
=COUNTIF(B2:B100,"<>")-H2
Adjust the ranges to suit (I have assumed that row 1 contains column headers).