Note on the interpretation of interactions in comparative research

Area of Science:

• Psychology
• Statistics
• Research Methodology

Background:

• Comparative research frequently focuses on interactions between subject groups and experimental treatments.
• Interpreting these statistical interactions presents known challenges for researchers.
• A specific conceptual difficulty regarding ordinal dependent variables has been under-examined.

Purpose of the Study:

• To highlight a common yet overlooked conceptual problem in interpreting statistical interactions.
• To explain how ordinal dependent variables can distort the perception of interactions.
• To improve the accurate interpretation of experimental results in comparative studies.

Main Methods:

• Conceptual analysis of statistical interaction.
• Examination of the properties of ordinal dependent variables.
• Illustrative examples of variable transformations and their impact on interaction effects.

Main Results:

• Dependent variables with only ordinal measurement properties can be transformed.
• These transformations can introduce spurious statistical interactions.
• Alternatively, genuine interactions may appear to vanish after transformation.

Conclusions:

• Researchers must be cautious when interpreting interactions involving ordinal dependent variables.
• The choice of measurement scale and transformations can significantly influence statistical findings.
• Careful consideration of measurement properties is crucial for valid comparative research.