Statistical results on restorative dentistry experiments: effect of the interaction between main variables.
Statistical analysis interpretation is a critical field in scientific research. When there is more than one main variable being studied in a research, the effect of the interaction between those variables is fundamental on experiments discussion. However, some doubts can occur when the p-value of the interaction is greater than the significance level.


OBJECTIVE
To determine the most adequate interpretation for factorial experiments with p-values of the interaction nearly higher than the significance level.


METHODS
The p-values of the interactions found in two restorative dentistry experiments (0.053 and 0.068) were interpreted in two distinct ways: considering the interaction as not significant and as significant.


RESULTS
Different findings were observed between the two analyses, and studies results became more coherent when the significant interaction was used.


CONCLUSIONS
The p-value of the interaction between main variables must be analyzed with caution because it can change the outcomes of research studies. Researchers are strongly advised to interpret carefully the results of their statistical analysis in order to discuss the findings of their experiments properly.
Cavalcanti
Andrea Nóbrega
AN
Department of Oral Rehabilitation, School of Dentistry, School of Medicine and Public Health of Bahia, Salvador, BA, Brazil. andreancavalcanti@yahoo.com.br
Marchi
Giselle Maria
GM
Ambrosano
Gláucia Maria Bovi
GM
D000818:Animals; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry / Q000145:classification; D003627:Data Interpretation, Statistical; D001840:Dental Bonding / Q000706:statistics & numerical data; D003764:Dental Materials / Q000737:chemistry; D018865:Dental Research / Q000706:statistics & numerical data*; D003793:Dental Restoration, Permanent / Q000706:statistics & numerical data*; D005163:Factor Analysis, Statistical; D006244:Hardness; D012107:Research Design / Q000706:statistics & numerical data*; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013696:Temperature; D013718:Tensile Strength
C438313:Clearfil SE Bond; D003188:Composite Resins; D003764:Dental Materials; C451600:OptiBond Solo Plus; D019279:Resin Cements; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate