In this paper, we systematically investigate different factors and their effects on the wireless transmission properties using a full-factorial experimental design of a wireless sensor network in a real-world indoor environment. We quantify the impact of primary factors such as the wireless channel, physical position, transmission power, and their interactions on the received signal strength (RSS). While some of our results support conventional assumptions, this study also shows that there are many properties which are in contrast to existing findings. For example, there is no significant correlation in the measured RSS between different but equally-distant transmitters, yet the correlation coefficient between two transmitters is above 94%. In addition, changing the wireless channel even in a static network scenario results in highly unpredictable interaction with other factors and significantly influences the measured RSS. Since the analyzed network only consists of low-cost, commodity transmitters, the results of this experimental analysis can serve as valuable insights in planning and deploying wireless sensor networks in different application scenarios.