Quality of reporting of descriptive and inferential statistics in negative studies published in Indian medical journals

Abstract

Aims and Objectives : It is observed that negative studies published in medical journals are underpowered to detect the actual difference between the groups, but no data are available on the quality of the statistics reported in these studies. Therefore, this study was carried out with aim of evaluating negative studies published in Indian medical journals for adequacy of reporting of descriptive and inferential statistics. Materials and Methods : All the original articles published in 14 Pubmed-indexed Indian medical journals were analyzed to determine whether the study was negative or positive. All the negative studies were analyzed for correctness of the descriptive statistics and inferential statistics. The types of data and statistical methods were also noted down. Descriptive statistics was used and values were expressed as frequency, percentages and confidence interval. Results : Incorrect descriptive statistics was mentioned in 15 (28.8%, 95% CI 18.3-42.2%) studies. Information related to assumptions of statistical tests were mentioned in only two (3.8%, 95% CI 1.0-12.9%) articles. Inappropriate/incorrect statistical tests was used in 22 (42.3%, 95% CI 29.8-55.8%) studies. The most common reason for inappropriate reporting of descriptive statistics was use of mean and SD for description of ordinal data. The most common reason for incorrect statistical test was use of parametric test for ordinal data. The most common statistical test was the t-test. Conclusion : Negative studies published in prominent Indian medical journals are statistically weak, and readers critically analyze these studies before making any opinion based on them.