The assembly quality is affected by various factors within which fixture variations are the most important. For that reason an extensive research on fixture variations has already been done. In this work we propose a linear models (LMs) application for the purpose of analyzing sources of variation in the fixture as well as establishing a model between positions of ingoing parts and measured geometrical characteristics of the assemblies. Objectives: (1) To estimate the strengths of different sources of variation on the assembled parts. (2) Estimate a regression model between the positions of ingoing parts as inputs (that are defined by positions of pins holding them), and measured geometrical characteristics as outputs, that can be used to determine which measured characteristics are influenced by which input variable. Methods: The data was experimentally collected in a laboratory environment by intentionally changing positions of ingoing part, assembling the parts and subsequently measuring their geometrical characteristics. We use liner model to establish the relation between geometrical characteristics measured on the assembled parts, and the input variables of interest. Results: Presented is a modeling technique that can be used to establish which measured geometrical characteristics are influenced by input variables (i.e.pins positions) of interest. The natural variation in the system (i.e. not modeled variation) is quite high. The time passed between measurements has a significant influence on measured values.