In this paper, we elaborate a set of scenarios and experiments for evaluating the impact of the physical environment on a Wireless Sensor Network (WSN). More specifically, a WSN application is implemented for collecting received signal strength indicator (RSSI) measurements in two different environments. The main contributions are twofold: boxplot diagrams are used for graphical comparison of RSSI measurements, and statistical analysis of variance (ANOVA) is performed for evaluating the impact of the physical environment on a WSN. Results analysis shows the conditions where the impact of the physical environment on a WSN is significant.