# How to calculate the mean of several variables when you have DK/NA values

To calculate the average of several variables, you need to know what you want to do when you have DK values. When you have at least one DK/NA value, in Askia Analyse or in AskiaVista, the sum of variables will be equal to DK:

**DK/NA** + *Var2* + *Var3* = **DK**

*Var1* + **DK/NA** + *Var3* = **DK**

*Var1* + *Var2* + **DK/NA** = **DK**

So, to handle the interview with a DK response, you have two possibilities:

**1. Removing the interview**

If you have at least one DK/NA value, you want to remove the full interview from the average calculation. *(Calculated variable Numeric by script):*

Dim arrQs As QuestionArray

arrQs.Push(^Q1^).Push(^Q2^).Push(^Q3^)

Dim arrVals = {}

Dim i

For i = 1 to arrQs.Count

If arrQs[i].Value <> DK Then

arrVals.Push(arrQs[i].Value.ToNumber())

Else

arrVals = {}

Exit for

Endif

Next i

If arrVals has {DK} Then

Return DK

Else

Return arrVals.Sum()/arrVals.Count

EndIf

**2. K****eep the interview and ignore the variable **

You have at least one **DK/NA** value, you exclude the variable from the calculation but you keep the interview for other valid variables *(calculated variable numeric by script):*

Dim arrQs As QuestionArray

arrQs.Push(^Q1^).Push(^Q2^).Push(^Q3^)

Dim arrVals = {}

Dim i

For i = 1 to arrQs.Count

If arrQs[i].Value <> NR Then

arrVals.Push(arrQs[i].Value.ToNumber())

Endif

Next i

Return arrVals.Sum()/arrVals.Count

You can also highlight all three variables in the Question tree > Create loop. The resulting looped variables can give you some additional flexibility to analyse the aggregated data of the source variables.