What about new developed constructs in PLS?

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AAljabr
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Real name and title: Abdulrahman Aljabr

What about new developed constructs in PLS?

Post by AAljabr » Fri Feb 12, 2016 8:35 am

Dear all,

I have an important and urgent question related to validating new constructs in the PLS context, and I really appreciated it if any one can assist me. Please provide me your comments and answers to my questions. Your assistance is highly appreciated.

I have read a lot about (1) exploratory factor analysis (EFA), including both common factor analysis and principle component analysis (PCA) and (2) confirmatory factor analysis (CFA).
What I understood from my intensive reading can be condensed into the following points, and please correct me if I am mistaken:

1. Researchers should use EFA before CFA if they have developed a new construct, which has not been tested by prior literature. (What I mean by a new construct is that although researchers might derive the construct from prior theoretical literature, the new construct has not been used by empirical studies in the way in which it was developed by researchers.) AM I right?

2. After exploring the structure of the new construct by using EFA, researchers should use CFA to confirm and validate the new construct with a new sample or part of their sample that has not been included when using the EFA test (i.e., half of the sample is used for EFA, and the another half is used for CFA). (This means that researchers should not conduct both EFA and CFA with the whole sample.) AM I right?

3. As all PLS constructs (reflective and formative) are composites, principle component analysis (PCA) is the applicable version of EFA. (This means that researchers should use PCA instead of common factor analysis in SPSS or other programs when evaluating the new construct before entering it into the measurement model (i.e., CFA in PLS). The new construct should be entered into the measurement model (CFA in PLS) based on the results of the PCA.) AM I right?

My case is:
1. I have developed a new construct, PC with 12 items.

2. I have derived this construct from prior theoretical literature. There is no study that has used the same combination of items that I have used to measure PC.

3. The construct is formative (i.e., most of the items are not interchangeable).

4. It is possible that the construct can be modeled as a second order construct with three or four first order constructs, but there is no strong theory that suggests which items should belong to each of the first order constructs. To be honest, I conducted PCA in SPSS, and found that PC has four factors (based on the Eigenvalue above 1 criterion) or one factor (based on Parallel analysis and MAP test criteria). It is difficult, however, to determine the number of factors based on the scree plot criterion (in particular, the one factor and four factors solutions are both possible).

I have tested both solutions (one factor solution and four factors solutions) in PLS, however, the results are not very good in relation to validating the first order formative constructs and the second order formative construct (i.e., PC). There were some instances of negative weights and weights above 1. I had to use Mode A or equal weights to solve these problems.

5. My sample size is 200, which means that it is difficult to divide it by 2 to run EFA for one half and CFA for the another half.


- Now, what is the best course of action regarding modeling PC in the measurement model in PLS?

Action 1: Should I conduct PCA before PLS and then using the PCA results to model PC in the measurement model?
This alternative is based on the fact that:
1. PC is a new construct.
2. PC is formative.
However, my sample size is relatively small to conduct both PCA in SPSS and CFA (in PLS).

Action 2: Should I conduct CFA only?
However, how can I know whether PC is a first order construct or second order construct since it is a new developed construct?
Should I model it in the model based on my own judgment and logical reasons?

AAljabr
PLS Expert User
Posts: 33
Joined: Wed Jan 06, 2016 11:52 pm
Real name and title: Abdulrahman Aljabr

Re: What about new developed constructs in PLS?

Post by AAljabr » Tue Feb 16, 2016 1:48 pm

Dear all,

Your answers and opinions are highly appreciated.

Thanks

AAljabr
PLS Expert User
Posts: 33
Joined: Wed Jan 06, 2016 11:52 pm
Real name and title: Abdulrahman Aljabr

Re: What about new developed constructs in PLS?

Post by AAljabr » Fri Feb 19, 2016 7:57 am

Dear SmartPLS developers and Experts,

We all would benefit from your advice about this issue.

Thanks

jmbecker
SmartPLS Developer
Posts: 1094
Joined: Tue Mar 28, 2006 11:09 am
Real name and title: Dr. Jan-Michael Becker

Re: What about new developed constructs in PLS?

Post by jmbecker » Tue Mar 15, 2016 7:39 pm

Many questions.

1. Not necessarily. If you have a clear definition of your constructs, you can also right away start with the confirmatory part. Yet, you should not drop indicators based on “CFA” results and then do another “CFA” on the same sample to assess model fit. That would be as bad as 2).
2. Definitive yes. If you decide to do an EFA before CFA, it should be on a different sample. A split-half is also not optimal, because the factor structure can depend on your specific sample, especially if you do not have a very high quality representative sample of your population. Hence, you should collect two different samples to validate the construct doing EFA and CFA.
Independent of the EFA & CFA questions I would always advice multiple sample for construct development. You should not build a new construct on just one limited sample.
3. Yes, PLS is more closely related to PCA than to traditional factor analysis.

Yet, in your case with a formative construct you will have problem anyway (also with a PCA), because it is still based on the correlation of the indicators. Yet, formative indicators must not be correlated and can still represent a single concept. Hence, EFA is not useful for formative constructs.

How, do you know that your construct is not multi-dimensional? Strong theory and face-validity. Those are the most important drivers in assessing a formative construct in the earlier stages of construct development.
Dr. Jan-Michael Becker, University of Cologne, SmartPLS Developer
Researchgate: https://www.researchgate.net/profile/Jan_Michael_Becker
GoogleScholar: http://scholar.google.de/citations?user ... AAAJ&hl=de

AAljabr
PLS Expert User
Posts: 33
Joined: Wed Jan 06, 2016 11:52 pm
Real name and title: Abdulrahman Aljabr

Re: What about new developed constructs in PLS?

Post by AAljabr » Wed Mar 16, 2016 6:12 pm

Dear Dr. Becker,

Many thanks for your valuable answers. I really appreciate your assistance.
All answers were very clear. However, I did not grasp the idea behind your question your final point:

How, do you know that your construct is not multi-dimensional? Strong theory and face-validity. Those are the most important drivers in assessing a formative construct in the earlier stages of construct development.



It is possible the question to be asked the other way around: how do you know your construct is multi-dimensional?

Could you please clarify your point?

Many Thanks,
Abdulrahman

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