"The Impact of Avalanche Transceivers on Mortality from Avalanche Accidents" by Hohrieder, et al takes a look at mortality with and without a transceiver. It looks at 194 accidents in Austria from 1994 to 2003 and analyzed the impact of transceivers on mortality.
The results show no significant difference in mortality. The relative risk ratio was -0.20 suggesting decreased risk had there have been a significant decrease in mortality, however, this was not the case. The P value showed an insignificant difference. The study was lacking in number of subjects (or power). I interpret this as a suggestion, rather than a fact, that there is relative risk reduction with the use of trancievers (beacons).
Another study on "The impact of avalanche rescue devices on survival" by Brugger et al in 2007, allows us to compare airbags and trancievers (beacons). This study held much more power, and showed an interesting outcome.
The airbag analysis showed a mortality of 2% and 18% with and without and airbag respectively, and a relative reduction in mortality of -0.9.
The tranciever anaylsis showed a mortality of 55% and 70% with and without a tranciever. Relative risk reduction was found to be -0.74. Interpretation: Comparing these two studies, relative risk reduction was more negative in the airbag (when compared to control) vs having a tranciever (vs control)
I would interpret this as follows:
Airbags and trancievers both significantly reduce your mortality (chance of death in the backcountry). Airbags decrease your mortality moreso than do trancievers given the limited number of studies on the topic, noted above.
Below is a chart with the data, taken from Brugger et al, 2007. This compares many different variables, those discussed above are included as well.
Please add your input. This is a very HOT topic and I would appreciate your input.