MS ACCESS 2007 syntax for an IIF "or".... /THEN statement that works in COGNOS

The cognos code seems to lack any parenthesis for cleanliness. I am surprised it returns the desired results. When you mix "And" and "Or", you'd better have parenthesis in order to establish your order of evaluation.

Regardless, the best way to get that much logic in access is to create a function.
I'm guessing at your datatypes, and set them to Decimal.

Public Function MyCognosLogic(Target As Decimal, Baseline As Decimal, _
                                                        SeeMeasure As Boolean) As Decimal

'Embed parenthesis in below If statement to partition your logic as desired.
If (Target < Baseline And _
    SeeMeasure = false Or _
    Target > Baseline And _
    SeeMeasure = true Then

            MyCognosLogic = Target
Else
            MyCognosLogic = Baseline - (Baseline * .05)      
End If
End Function

Select allOpen in new window

Once you've defined this in a module in your access file. reference it in your query by calling it like this:

TG: MyCognosLogic([TmsrAmt]![Target],[baseline],[Do we want to see an increase in this Measure?])

Unsatisfactory solution

The following should work:

IIF([PM View prd].[DataTarget History].[Target] < [PM View prd].[Data].[Baseline] AND [PM View prd].[Data].[Do we want to see an increase in this Measure?] = 0, [PM View prd].[DataTarget History].[Target], IIF([PM View prd].[DataTarget History].[Target] > [PM View prd].[Data].[Baseline] AND [PM View prd].[Data].[Do we want to see an increase in this Measure?] = 1, [PM View prd].[DataTarget History].[Target], [PM View prd].[Data].[Baseline] -  ([PM View prd].[Data].[Baseline] * .05)))

Not quite.  
Both IIF statements produce the same result.  In My COGNOS statement noted above, you will notice an "OR"  which somehow needs to be included.
Your sugestion reproduced in ACCESS systax below does the same as my above noted ACCESS syntax:

TG: IIf([TmsrAmt]![Target]<[baseline] AND
[Do we want to see an increase in this Measure?]=0,
[TmsrAmt]![Target] ,

-------here i need:  
                  {on the other hand}  
{OR}


IIf([TmsrAmt]![Target]>[baseline] AND
[Do we want to see an increase in this Measure?]=1,
[TmsrAmt]![Target] ,
 [baseline]-([baseline]*0.05))
__________________
Below is the syntax you provided whch implies an "and" before the 2nd "IIF(...", when I need the syntax that will make it an "or" clause:

IIF([PM View prd].[DataTarget History].[Target] < [PM View prd].[Data].[Baseline] AND
[PM View prd].[Data].[Do we want to see an increase in this Measure?] = 0,
[PM View prd].[DataTarget History].[Target],

                  {on the other hand}  
{OR}

IIF([PM View prd].[DataTarget History].[Target] > [PM View prd].[Data].[Baseline] AND
[PM View prd].[Data].[Do we want to see an increase in this Measure?] = 1,
[PM View prd].[DataTarget History].[Target],
[PM View prd].[Data].[Baseline] - ([PM View prd].[Data].[Baseline] * .05)))

Your logic was right.
I finnally got the ACCESS syntax needed to work by applying an appropriate (-) sign and an extra parenthesis:

TG: IIf([TmsrAmt]![Target]<[baseline] And [Do we want to see an increase in this Measure?]=0,[TmsrAmt]![Target],IIf([TmsrAmt]![Target]>[baseline] And [Do we want to see an increase in this Measure?]=-1,[TmsrAmt]![Target],[baseline]-([baseline]*0.05)))