You could look at Debra Dalgleish's site:
http://www.contextures.com/xlFunctions02.html

It might help with the questions caused by excel's help for =vlookup().

jc33 wrote:

Can you please define each paramater that needs to be entered?
lookup_value
table_array
col_index_num
range_lookup

"Gary''s Student" wrote:

Create a simple table of two columns. The first column could be the
concentration in the desired units i.e. micrograms per litre. The second
column could be the inhibitory effect from 0% to 100%. Then you can use
VLOOKUP() to find the approximate 50% level.
--
Gary''s Student


"Fred Smith" wrote:

First you need to tell us what IC50 is.

--
Regards,
Fred


"jc33" wrote in message
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Dave Peterson