Combining two scales into one

[steph88]

Hello!

I am trying to merge two scales into one; one measures maternal warmth and the other measures paternal warmth. I have tried to simply add the two variables together in the "compute variable" tab. However, when looking at the frequencies of this variable, I lose almost half of the respondents answers. Is there a way to merge these two variables together into one without losing any of the respondents answers? Any assistance would be great.

Steph

 

[Englund]

Do you have any missing values?

 

[steph88]

Do you have any missing values?

Yes, I do.

 

[hlsmith]

Well, that can typically be a problem. Because missing is not equal to "0".

Is this your problem?

 

[Englund]

That may be a problem. When z=x+y is being carried out, z[a]=x[a]+y[a] may be set to NA (not a number or missing value) if x[a] and/or y[a] is NA.

 

[steph88]

So does this mean that I need to recode the missing values to zero and then combine them?

 

[Englund]

That's one way, yes. Make sure you don't already use zero in any of the variables though.

 

[noetsi]

In SAS if you have a missing value and you do any type of calculation it will automatically not do that calculation. Sum (X+y+z) will yield a missing value I believe if any of x y or z is missing.

 

[Lazar]

One way to do it is to ask for the mean of the items rather than there sum. I believe that will give you a value when at least one of the items is filled out. Given there are missing values and you have not imputed, the mean is most likely better anyway.