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The knowledge of statistical analysis is essential before planning any research study or undergoing any orthodontic treatment. Clinical studies often compare the efficacy of a new treatment in a study group with the efficacy of conventional treatment or with a control group. Aside from a pure description, we should know whether the observed differences between the treatment groups are just random or are really present. This article informs the reader about frequently used statistical tests and their application in orthodontics and also provides a brief overview of the type of statistical tests to analyze research data with its examples.

It is a prospective, in-vivo randomized cross sectional questionnaire based study to determine general esthetic preference of Indian population and to find out whether this preference was affected by sex, age, education, social status and geographic location. Toward these aims, 30 well balanced facial profiles are selected (15 males and 15 females) in the age group of 18-30 years. The most attractive facial profile of 1 male and 1 female subject is selected by three panel of Judges. Profile selected for each sex were morphed by an Adobe Photoshop version cs2 technique and then scored by 200 participants. Subjects were asked to rank the profiles in ascending order of attractiveness on scoring scale 1 to 10. Morphing is done in 2 dimensions Sagittal and Vertical. Profile digital photographs were altered by 2mm and 4mm increments to produce different combinations of mandibular sagittal positions and vertical facial heights and to assess whether interactions and magnitude of the sagittal and vertical facial dimensions influence perception of facial attractiveness. Analysis of variance (ANOVA) and independent sample t-tests were used to compare the preferences of the groups. The orthognathic profile and straight profile in both sexes was selected as the most preferred profile whereas the convex profile with a prognathic maxilla and a retrognathic mandible were the least preferred. The public also admired fuller and protrusive lips in females and retrusive lips in males. Sex, age, education, social status and geographic location were also shown to affect the public’s profile preferences. Keywords: ANOVA, facial perception morphing questionnaire study ttests.