If function when you want to use text not a number

no, that is not what I wanted. sorry if I was unclear.

ok imagine this (btw, easier if I could upload an example):

column A and column b contain first and second name. then column C asks whether they are clinical/non clinical. column D then asks what sub-set clinical they are. some people will be blank as they are non clinical, this is fine. some will say 'gp', 'nurse' etc. I want to create a further column of 'public health' (i.e. colun E), which essentially would say 'yes' or 'no' if someone has answered GP or Practice manager in column D. i.e. we have identified that they are clinical, we identify that they are a subset and now we want to further categorise them.

so I want to put an IF forumula in column E, to say; if in column D they have said GP, then column E for whether they count as public health should say ;yes', otherwise, 'no'