Your chances of working your way up the Star Trek command hierarchy were greatly enhanced if you did not wear a red shirt as part of your uniform.
Recent analysis of crew mortality rates shows that 73 per cent of USS Enterprise crew members, from the original “five-year mission”, died while wearing a red shirt.
The Enterprise has a crew of 430 (startrek.com) in its five-year mission. (Now, I know that the show was only on the air for 3 years, but bear with me. 80 episodes were produced, which gives us the data to build from.) 59 crewmembers were killed during the mission, which comes out to 13.7% of the crew. So, that will be our overall conversion rate, 13.7%. However, we need to segment the overall mortality (conversion) rate in order to gain the specific information that we need: Yellow-shirt crewperson deaths: 6 (10%), Blue-Shirt crewperson deaths: 5 (8 %), Engineering smock crewperson deaths: 4, Red-Shirt crewperson deaths: 43 (73%)
The risk of being a “red shirt” had clearly abated by the time the TNG crew took to the space ways though.