One option is to have a single cell with Data Validation which provides a
list of your tests. This will only allow the selection of one item and you
could test to see if there was an entry.

If this approach is exceptable, please let me know and I'll explain further
if required.

How is your data currently organised i.e. how is a test selected?

"cfspahn24" wrote:

I have to have te user select a test they performed on a patient, they must
select a test, but only one test; How can I force tem to: a. choose a test,
and b. select only one test? I am a novice at programming so please take me
step by step. Thanks!!