Wanting to retrieve values from external workbook by searching name of column.

Then instead, you might want to use this formula:

Solution

=LARGE(Signals.csv!$B$1:$B$69,1)

Be sure to change the column to the appropriate name.

Also, the LARGE function looks for the Nth largest number.
So 1, is the first largest. 2 is the second and so on.

if you used the formula as shown (with adjustments for column) $B,$C and so on
You should get results more akin to what you're looking for.

Tip
In the future, you might want to keep the names you are looking up on the same orientation for lookup purposes.
Then the existing formula would be something like:

=LARGE(Signals.csv!SNR_average_dB,1)

Hope that helps.

I tried using the LARGE function on it's own with the column name inserted (SNR_average_dB) and its returning '#NAME?'. Do I have to combine HLOOKUP & LARGE or just use LARGE?

Thanks!