The study was conducted in Kerman, the largest province of Iran that is located 895 kilometers south of the capital. The Ethical Committee of Kerman University of Medical Science approved this study with code number: 620. For convenience, we randomly selected our subjects who were the participants of Kerman Dental School Clinics and an interviewer-administered questionnaire was used to collect the data. Two Iranian dentists, fluent in English performed a forward translation. The translated text was translated back into English by two English and literature graduates. Thereafter, in one session under the supervision of the Research Center, these four people discussed and approved unanimously that the translation was the same as the original English version.
The reliability was examined by measuring internal consistency reliability and reproducibility.
Internal consistency reliability was assessed by examining internal consistency (Cronbach‘s alpha) and item-total correlation.
Reproducibility was evaluated by measuring test-retest reliability. Test-retest reliability was calculated using intraclass correlation coefficient (ICC). A sample of 60 respondents was interviewed two weeks after the first interview.
Responsiveness of an instrument is the ability to detect important changes over time. It was evaluated by calculating the effect-size (ES) and Standardized Responses Mean (SRM) by computing pre-intervention and post-intervention mean OHIP scores. They were analyzed in a subgroup of 40 patients treated with dental extraction of one painful tooth that no longer served a purpose. All these treatments were performed by an experienced dentist.
Validity refers to the extent to which the instrument measures what it is supposed to measure. The method of known-group comparison was used to determine the degree to which the OHIP was able to discriminate between mutually exclusive subgroups of subjects. It was expected that subjects with more than 25 teeth that had condition such as better self-rated oral health and less frequently referred to a dentist, and those who perceived that they did not need dental treatment, would show lower OHIP scores than those without these conditions. Construct validity was tested by using Student’s t-test and correlation coefficient (Pearson).
The reliability was examined by measuring internal consistency reliability and reproducibility.
Internal consistency reliability was assessed by examining internal consistency (Cronbach‘s alpha) and item-total correlation.
Reproducibility was evaluated by measuring test-retest reliability. Test-retest reliability was calculated using intraclass correlation coefficient (ICC). A sample of 60 respondents was interviewed two weeks after the first interview.
Responsiveness of an instrument is the ability to detect important changes over time. It was evaluated by calculating the effect-size (ES) and Standardized Responses Mean (SRM) by computing pre-intervention and post-intervention mean OHIP scores. They were analyzed in a subgroup of 40 patients treated with dental extraction of one painful tooth that no longer served a purpose. All these treatments were performed by an experienced dentist.
Validity refers to the extent to which the instrument measures what it is supposed to measure. The method of known-group comparison was used to determine the degree to which the OHIP was able to discriminate between mutually exclusive subgroups of subjects. It was expected that subjects with more than 25 teeth that had condition such as better self-rated oral health and less frequently referred to a dentist, and those who perceived that they did not need dental treatment, would show lower OHIP scores than those without these conditions. Construct validity was tested by using Student’s t-test and correlation coefficient (Pearson).
