A Study on Patents Invalidation Reexamination Decisions for Discussing Variance between Strong Utility Models and Weak Utility Models

19,082 China utility model patents were retrieved from invalidation reexaminations decisions. A thorough analysis using ANOVA was conducted across nine technology areas for discussing the variances between weak utility models, in any of which all claims were invalid through the reexaminations, and strong utility models, in any of which at least one claim was remaining valid. Four high value indicators for classifying utility models were found, including description word count, examination duration, figure count and claim count, to respectively show significance in five technology areas; wherein the strong patents showed significantly higher means of indicators in every technology areas of significance. Two fair value indicators for classification were found, including IPC count and abstract word count, to respectively show significance in three technology areas. Two low value indicators for classification were found, including inventor count and applicant count, showing significance in two or less technology areas. Technology distinction was shown. The overall technology and technology G (physics) were respectively provided with the most number of five valuable indicators, while technology C (chemistry and metallurgy) and D (textiles; paper) were respectively provided with the least number of three valuable indicators. The technologies provided with more valuable indicators were more applicable for classifying strong/weak utility models. The strong utility models were shown to be provided with more claim terms, more figures, richer description content and longer examination duration. The criteria for classification was therefore obtained.