Vlookup for comparing values

Hi Sophia. ISERROR is there to test whether the first VLOOKUP finds a cell with VALUE! or REF! in it. If it does find either of those it will return a TRUE value and your output will be the value if true in your IF statement (in this case, ""). If the VLOOKUP finds something, ISERROR will return false and the IF statement will perform the value if false lookup expression. ISERROR has been included in this formula because you have cells in your source data which either don't contain anything or have error keywords in them. You could simplify the formula by removing any such errors in the data but this might not be viable. As it stands, your formula structure is used widely to perform conditional lookups so without looking at the source data I think you may be stuck with it.

The best way to understand such formulas is to build them yourself. As an exercise, simply ask yourself how you would go about getting the results you need through a formula. If you start to build it you'll almost certainly end up with a similar formula, only it will make a lot more sense!

Hope this helps,

Anthony