externalities based on interpretations derived from observable data and general networking principles [@salamatian2003cross; @weinsberg2011inferring].

![Diurnal Patterns of Throughput Measurements, Iran, Jan - Mar 2013[]{data-label="figure:mathishard:diurnal"}](resources/IR-Throughput_Diurnal_2013.png){width="\textwidth"}

The extent of externalities often vary based on diurnal patterns of use and in response to specific incidents. Using the performance metric of throughput, Figure \[figure:mathishard:diurnal\] demonstrates that observed network speed is higher in the early hours of the morning, Iran time (GMT +4:30), than during the day. These trends are mirrored in the performance across the week, and within other measurements, such as packet loss. It would appear that Iran’s network does not handle the additional load of office hours and evening use gracefully.

M-Lab-based services attempt to perform testing under favorable conditions by selecting the measurement server by geographic proximity. These servers are physically located across the world, including in Australia, Austria, Czech Republic, France, Germany, Greece, Japan, Ireland, Italy, the Netherlands, New Zealand, Norway, Spain, Slovenia, Sweden, Taiwan, the United Kingdom and the United States. Although one of these M-Lab hosts countries directly peers with Iran,[^5] the selection mechanism predominantly directed NDT clients to Greece (of the 2921 tests in January 2013, 50.39%), United States (22.08%), United Kingdom (16.40%) and France (9.28%), with 