CB-SEM using #SmartPLS4 - 2 - An Introduction to Structural Equation Modeling (SEM)
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Covariance-based SEM is presented as a solution for complex causal models that include multiple mediators and higher-order constructs within a single analysis.
Briefing
Structural equation modeling (SEM) is positioned as the right tool for testing complex causal frameworks—especially when multiple mediators, indirect effects, and higher-order constructs appear in the same model—because it can evaluate measurement quality and structural relationships simultaneously. The session frames a common research scenario: antecedent variables influence “KM processes” and “organizational performance” indirectly through “creative organizational learning.” That kind of multi-path, multi-construct setup can be difficult to handle in SPSS, particularly when the design requires more than one mediator or serial/compound mediation within a single integrated model.
With SmartPLS 4, the workflow expands beyond variance-based SEM by adding an option for covariance-based SEM. The series outline lays out a progression from basics to advanced applications: building measurement and structural models, checking reliability and validity, improving model fit, and then moving into mediation, moderation, and higher-order construct analysis. Before any modeling begins, the session emphasizes that constructs must be measured with multiple questionnaire items—typically at least four to six per construct—because SEM relies on indicators to represent latent (unobserved) variables, and item deletion can occur during assessment.
SEM itself is defined as a family of techniques that examines relationships among many variables at once, using a confirmatory approach. Rather than running separate regressions, SEM tests whether observed data provide evidence for hypothesized directions and significances within a proposed theoretical framework. The method is described as combining elements of factor analysis (to assess measurement properties like reliability and validity) with regression-like modeling (to test how predictors influence outcomes). A key advantage highlighted is the ability to model multiple independent and dependent variables, incorporate error terms, and handle constructs that can act as predictors, mediators, moderators, or even controls within the same system.
The modeling process is split into two core sub-models. First comes the measurement model, assessed through confirmatory factor analysis (CFA), which checks whether items (indicators) properly measure their intended latent constructs and whether constructs are distinct enough to show discriminant validity. Second comes the structural model, assessed by testing the significance of hypothesized paths—often using t statistics to determine whether relationships exceed a threshold for statistical significance. In this framework, constructs are represented as latent variables (circles/ovals), questionnaire items as manifest variables (rectangles), and arrows indicate directional influence.
The session closes by clarifying SEM terminology—exogenous versus endogenous latent variables, factor loadings as the strength of association between constructs and indicators, and t statistics as the criterion for path significance—then sets expectations for subsequent theoretical and practical sessions focused on using SmartPLS for covariance-based SEM.
Cornell Notes
The session argues that structural equation modeling (SEM) is the best fit for research models with complex relationships—such as multiple mediators, indirect effects, and higher-order constructs—because it evaluates measurement and structural paths together. It highlights that SmartPLS 4 supports covariance-based SEM, expanding options beyond variance-based approaches. SEM uses a confirmatory framework: researchers specify hypothesized relationships from theory, then test whether data support those directions and significances. The workflow is split into a measurement model (CFA to assess reliability/validity and discriminant validity) and a structural model (path significance testing using t statistics). Constructs are latent variables measured by multiple indicators, so using at least four to six items per construct is recommended.
Why can SPSS struggle with certain mediation designs, and what does SEM add instead?
What is the recommended item strategy for measuring constructs in SEM?
What are the two sub-models in SEM, and what does each one test?
How do factor loadings and t statistics function in SEM evaluation?
How are exogenous and endogenous latent variables distinguished in SEM path diagrams?
Review Questions
- What are the main differences between the measurement model and the structural model in SEM, and what does each one evaluate?
- How do factor loadings and t statistics help determine whether indicators and paths are acceptable in SEM?
- Why does SEM treat constructs as latent variables, and what practical implication does that have for questionnaire design?
Key Points
- 1
Covariance-based SEM is presented as a solution for complex causal models that include multiple mediators and higher-order constructs within a single analysis.
- 2
SmartPLS 4 adds an option for covariance-based SEM, complementing variance-based SEM approaches.
- 3
Constructs should be measured with multiple indicators—at least four to six items per construct—to reduce the risk of losing measurement coverage during item evaluation.
- 4
SEM uses a confirmatory approach: theory specifies hypothesized relationships, and the model is tested against observed data for directionality and significance.
- 5
SEM is evaluated through two sub-models: a measurement model (CFA for reliability/validity and discriminant validity) and a structural model (path significance testing).
- 6
Factor loadings quantify how strongly indicators measure their latent constructs, while t statistics determine whether structural paths are statistically significant.
- 7
Latent variables can be exogenous, endogenous, or both depending on whether they have incoming and/or outgoing arrows in the path diagram.