[Validation of short-form Nepean dyspepsia index in Iranian patients with functional dyspepsia]

Background: studying the validity and reliability of short-form ]SF[-Nepean Dyspepsia Index ]NDI[ in patients with functional dyspepsia ]FD

Materials and Methods: after translating to Persian, the NDI-10 was filled out by 210 patients with FD, whose disease had been diagnosed by a gastroenterologist based on Rome 3 criteria, who admitted to Gastroenterology Clinic of Afzalipour Hospital in 2015. The reliability of the questionnaire was studied by test-retest and Cronbach's alpha coefficient. The validity of the questionnaire was evaluated through content-validity and criterion-validity

Results: through analyzing the results of test-retest of the questionnaire, the Pearson coefficient was obtained as 83%, which proves the reliability of the questionnaire. Criterion-validity with the correlation coefficient of 0.56 and content validity both proves the adequacy of questionnaire for measuring the quality of life in patients with FD

Conclusion: generally, Persian translation of this questionnaire has acceptable validity and reliability for measuring the quality of life in patients with FD

[Evidence-based statistics: appropriate approach for description and analysis of research data]

In recent years using statistics in medical sciences is increasing and statistics is an essential part of each research. At present, for each study design, and for each type of data, there are appropriate statistical methods, which yield to valid results and inferences. Familiarity with such methods is essential, especially for those involved in the field of medical research, as they might confuse majority of readers who are not familiar with details of statistical analysis and data interpretation. Other consequences include waste of money, time, and energy spent for each research project. In recent years some papers have been published to enhance researchers' knowledge of statistics and its application in research methodology, but still there are many methodological mistakes in manuscripts. In this article we aim to demonstrate appropriate methods for data analysis. We will discuss importance of confidence intervals and their advantages over P-value. We will finally highlight common errors in data analysis such as univariate methods, ignoring power in detection of difference between groups, and using correlation coefficient to assess the agreement between scores