Additive Index Moderator treatment in SMARTPLS

Frequently asked questions about PLS path modeling.
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PLS Junior User
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Joined: Fri May 18, 2018 11:34 am
Real name and title: Mr. Alessandro Grillo

Additive Index Moderator treatment in SMARTPLS

Post by Alexg » Tue Jun 19, 2018 12:32 pm

Hello everyone,

I have a variable which is measured by a simple additive index of correct answers to closed-ended questions (I.e. correct answers are coded as "1" and incorrect and don't knows are coded as "0". Right answers will then be added to give the final score to each respondent). I have 10 questions for that variable so each respondent can score from 0 to 10.

The variable is a moderator.

In SMART/PLS may I include such variable using the final single score of each respondent? If so, would that variable be regarded as a single item construct? Hence, should I take all the needed precautions related to single items constructs?

Thank you in advance for your help!!!

SmartPLS Developer
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Joined: Tue Mar 28, 2006 11:09 am
Real name and title: Dr. Jan-Michael Becker

Re: Additive Index Moderator treatment in SMARTPLS

Post by jmbecker » Tue Jun 19, 2018 1:27 pm

Yes, it is modeled as a single item construct. In PLS a single item construct is the same as a single observed variable. The construct and item are the same. SmartPLS therefore only allows single items constructs and no directly observed single variables (because they are the same anyway and it is easier to handle).

I would say that your variables does not fall into the typical distinction between multi-item and single-item scales as it only exists as a single item.
Dr. Jan-Michael Becker, University of Cologne, SmartPLS Developer
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