Use of statistical analysis in the AJR and Radiology: frequency, methods, and subspecialty differences

The statistical procedures appearing in Radiology and the AJR were analyzed to determine the types of statistical tests used in major articles, their relative frequencies, and whether these methods differed according to radiologic subspecialty.

Six hundred sixty-nine major articles published in Radiology or the AJR during 1993 were reviewed for statistical content. These articles were first classified by radiologic subspecialty or principal focus according to the named journal section where each appeared (e.g., breast imaging, musculoskeletal radiology, neuroradiology). The statistical methods used in each article were then assigned to one of 18 categories (e.g., descriptive, basic t- and z-tests, correlation/regression techniques, and nonparametric statistics).

Of the 669 major articles analyzed, 294 (44%) used no statistical methods or descriptive statistics only, 179 (27%) used only one type of statistical method, 102 (15%) used two methods, and 94 (14%) used three or more methods. Statistical techniques were most likely to be used in articles classified as cardiac (85% used statistical analysis) or contrast agents (79%), but least likely to be used in gastrointestinal/abdominal imaging (45%), radiotherapy (44%), or miscellaneous topics (29%). Five basic categories of statistical methods--basic z- and t-tests, basic decision statistics (sensitivity, specificity), basic contingency table analysis (chi 2, McNemar), correlation/regression techniques (linear regression, Pearson coefficients), and basic nonparametric tests (Wilcoxon, Mann-Whitney U)--account for the complete statistical analysis appearing in approximately 80% of the major articles.

Approximately half the major articles appearing in Radiology or AJR used no statistics, descriptive analysis only, or a simple inferential test employing t-tests or confidence intervals; advanced statistical techniques were found in only 20% of articles. Statistical analysis was most likely to be used in articles dealing with cardiac radiology or contrast agents and least likely to be used in articles on abdominal/gastrointestinal radiology, radiotherapy, and miscellaneous radiologic topics.