Defining Effect Size Standards in Temporomandibular Joint and Masticatory Muscle Research

Area of Science:

• Dental research
• Biostatistics
• Musculoskeletal research

Background:

• Interpreting effect sizes is crucial in health research for assessing experimental results.
• Standardized guidelines for effect size interpretation are lacking in temporomandibular joint (TMJ) and masticatory muscle studies.
• This study addresses this gap by proposing new interpretation guidelines.

Purpose of the Study:

• To propose standardized guidelines for interpreting group differences in TMJ and masticatory muscle research.
• To establish thresholds for small, medium, and large effect sizes in this field.
• To enhance the reliability and relevance of findings in TMJ research.

Main Methods:

• Bibliometric analysis of meta-analyses from top-ranked dental journals.
• Inclusion of 16 meta-analyses encompassing 456 studies and 26,662 participants.
• Analysis of effect size metrics (Cohen's d, Hedges' g) and calculation of 25th, 50th, and 75th percentiles.

Main Results:

• For group differences, Hedges' g percentiles were 0.11 (25th), 0.34 (50th), and 0.74 (75th).
• These values suggest thresholds for effect size interpretation in TMJ and masticatory muscle research.
• The proposed thresholds are 0.1 for small, 0.3 for medium, and 0.7 for large effects.

Conclusions:

• Researchers studying TMJ and masticatory muscles should adopt the proposed effect size thresholds.
• These guidelines facilitate standardized interpretation of Cohen's d and Hedges' g.
• Adoption of these guidelines will improve the consistency and impact of research in this domain.