The influence of porosity on the trapped field achievable in 22 YBCO bulk superconductors of different sizes has been investigated and evaluated using Spearman's correlation coefficient in order to explore the significance of these critical features in a statistically significant way. The diameter of the single grain YBCO bulk sample correlates strongly with trapped field, and significantly more so than the effect of porosity. Therefore, the direct effect of porosity on the average Jc was investigated as the main aim of this investigation. A correlation was found between the average Jc calculated from trapped field measured at the top and bottom of the single grain and the porosity of the sample. This observation suggests that any method of reducing the porosity may significantly improve Jc and trapped field.