Re identifying the differences between the columns
You aksed how to identify people who werent in either of the 2 conferences. Do you mean people who went to one conference but not the other ?
If you do then a conditional format will do the trick
Use the "use a formula to determine wich cells to format"
enter the following formula for the Column A cells . Formula will show people in column A who did not attend the Column B conference
=ISNA(VLOOKUP(A2,B:B,1,FALSE)) and select a format
enter the following formula for the Column B cells . Formula will show people in column B who did not attend the Column A conference
=ISNA(VLOOKUP(B2,A:A,1,FALSE)) and select a format
(by the way this worls regardless of whether the columns are sorted or not)
