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Moderation Analysis with Categorical Variables using SmartPLS3 thumbnail

Moderation Analysis with Categorical Variables using SmartPLS3

Research With Fawad·
5 min read

Based on Research With Fawad's video on YouTube. If you like this content, support the original creators by watching, liking and subscribing to their content.

TL;DR

Create dummy variables for the categorical moderator and use only one dummy while treating the other category as the reference group.

Briefing

The analysis tests whether “type of Bank” (public vs. private) changes how two predictors relate to “collaborative culture” in SmartPLS. The core finding is that bank type significantly moderates both relationships: (1) perceived organizational support (POS) → collaborative culture and (2) organizational commitment (OC) → collaborative culture. Adding these moderation effects increases the model’s explanatory power, indicating that bank type meaningfully changes the strength of the underlying links.

Before running moderation, the workflow starts with creating dummy variables for the categorical moderator. “Type” is coded so that one category is the reference group, and only one dummy variable is used in the model. In the example, the dummy coding is arranged such that the moderator value 0 represents private sector banks and 1 represents public sector banks (with the alternative dummy treated as the reference). This setup is essential because SmartPLS moderation with categorical variables relies on interaction terms built from the dummy-coded moderator.

The moderation analysis is implemented using the product indicator approach. That choice depends on how the constructs are measured: because the independent variables are treated as reflective, the product indicator approach is selected. For the interaction term generation, the analysis uses the unstandardized option, and the interaction effects are added by selecting the endogenous variable that each predictor moderates. Two separate moderating effects are created: one for OC × type of bank and another for POS × type of bank. Each moderating effect is renamed to keep results interpretable.

Model evaluation begins with a baseline run (without moderation). The R² value is 0.542. After adding the interaction effects, the model is re-run to obtain the updated R². With moderation included, R² rises to 0.570. The difference between included and excluded R² is about 0.028—small in magnitude, but reported as statistically significant. Bootstrapping is used to test significance, with 500 resamples in the demonstration and a two-tailed test because no directional hypothesis is imposed.

To interpret moderation beyond significance, the analysis uses interaction plots and focuses on line steepness by group. For POS → collaborative culture, the public sector group (moderator = 1) shows a steeper positive gradient than the private sector group (moderator = 0). The reported coefficients used for plotting include a POS path coefficient of 0.428, a moderator main effect of −0.012, and an interaction coefficient of 0.345. The steep public-sector slope implies that higher POS is more strongly associated with higher collaborative culture in public sector banks.

For OC → collaborative culture, the moderation pattern reverses. The interaction coefficient is negative (−0.353), meaning the OC → collaborative culture relationship is stronger in private sector banks than in public sector banks. The OC path coefficient is reported as 0.387, and the negative interaction indicates that as the moderator shifts from private (0) to public (1), the OC effect weakens. In practical terms, organizational commitment predicts collaborative culture more strongly in private sector banks, while perceived organizational support predicts it more strongly in public sector banks.

Overall, the procedure demonstrates how to operationalize categorical moderation in SmartPLS using dummy coding, product indicator interaction terms, bootstrapping, and interaction plots to determine which group shows the stronger effect.

Cornell Notes

Bank type (public vs. private) significantly moderates two relationships with collaborative culture in SmartPLS. After adding moderation terms, R² increases from 0.542 (no moderation) to 0.570 (with moderation), a small but significant gain. The POS → collaborative culture link is stronger in public sector banks, shown by a steeper positive interaction-plot slope for the public group (moderator = 1). In contrast, the OC → collaborative culture link is stronger in private sector banks, indicated by a negative interaction coefficient (−0.353) and a steeper slope for the private group (moderator = 0). Interaction plots are used to interpret the direction and strength of effects across groups.

How are dummy variables created for a categorical moderator like “type of bank” in SmartPLS moderation?

The categorical variable is transformed into dummy variables using SmartPLS’s Transform → Create Dummy Variables. With two categories (public vs. private), two dummy variables are produced, but only one is used in the analysis because the other category serves as the reference group. In the example, the retained dummy is coded so that 0 represents private sector banks and 1 represents public sector banks (the alternative dummy is treated as the reference).

Why does the analysis use the product indicator approach and unstandardized product term generation?

The product indicator approach is selected when the independent variable(s) involved in the interaction are measured reflectively. For the interaction term generation, the unstandardized option is used for the categorical moderator setup. This combination determines how SmartPLS constructs the interaction terms used in the moderation effects.

What steps add moderation effects for two different predictors (OC and POS) in SmartPLS?

Each moderation effect is added by right-clicking the endogenous variable that the predictor moderates, then selecting Add Moderating Effect. The moderator is set to “type of bank,” and the independent variable is set to either OC or POS. Product term generation is kept as product indicator approach with unstandardized settings. The moderating effects are then renamed (e.g., moderation_OC_type, moderation_POS_type) to simplify interpretation.

How does the model’s explanatory power change after adding moderation, and how is that interpreted?

R² is first computed without moderation: 0.542. After adding both interaction effects, R² is recomputed: 0.570. The difference (included minus excluded) is about 0.028, described as small but statistically significant. This indicates the moderation terms add incremental explanatory value beyond the baseline model.

How do interaction plots determine which group has the stronger effect?

The analysis interprets moderation by comparing the steepness of the lines in the interaction plot. The group with the steeper slope shows the stronger relationship between the independent variable and collaborative culture. For POS → collaborative culture, the public sector line (moderator = 1) is steeper and positively sloped, implying POS has a stronger positive association with collaborative culture in public banks. For OC → collaborative culture, the private sector line (moderator = 0) is steeper, and the interaction coefficient is negative (−0.353), implying OC’s effect is stronger in private banks.

What do the sign and magnitude of interaction coefficients imply in this example?

For POS moderation, the interaction coefficient is positive (0.345), aligning with a stronger POS → collaborative culture relationship in public sector banks. For OC moderation, the interaction coefficient is negative (−0.353), aligning with a stronger OC → collaborative culture relationship in private sector banks. The sign indicates whether the relationship strengthens or weakens as the moderator moves from private (0) to public (1).

Review Questions

  1. When you have a two-category moderator, why is only one dummy variable used in SmartPLS moderation models?
  2. What does a positive vs. negative interaction coefficient mean for how the independent variable’s effect changes across private (0) and public (1) groups?
  3. How should you use line steepness in an interaction plot to decide which bank type shows the stronger relationship?

Key Points

  1. 1

    Create dummy variables for the categorical moderator and use only one dummy while treating the other category as the reference group.

  2. 2

    Use the product indicator approach for moderation when the interacting constructs are reflective.

  3. 3

    Generate interaction terms using unstandardized product term generation for the categorical moderator setup.

  4. 4

    Add separate moderating effects for each predictor that is expected to be moderated (OC × type of bank and POS × type of bank).

  5. 5

    Use bootstrapping to test significance of moderation effects (two-tailed when no direction is hypothesized).

  6. 6

    Compare R² before and after adding moderation to quantify incremental explanatory power.

  7. 7

    Interpret moderation using interaction plots by focusing on which group’s line is steeper to determine where the relationship is stronger.

Highlights

R² increases from 0.542 to 0.570 after adding both moderation effects, indicating a small but significant improvement.
Bank type significantly moderates both POS → collaborative culture and OC → collaborative culture.
Public sector banks show a stronger positive POS → collaborative culture relationship (steeper public-sector slope).
Private sector banks show a stronger OC → collaborative culture relationship, supported by a negative interaction coefficient (−0.353).

Topics

  • SmartPLS Moderation
  • Categorical Dummy Variables
  • Product Indicator Interaction
  • Interaction Plots
  • R Square Change

Mentioned

  • PLS
  • OC
  • POS
  • CC