I found this after reading and responding to this post here about early Trek fans' prejudicial negative reaction to TNG. One of my responses (see here) was to point out that any fans of the progressiveness of Trek ought to have been mindful of the room for improvement over TOS, with female representation being an obvious issue. I posed the question "when did Trek start consistently passing the Bechdel test", thinking that it didn't start happening until Voyager, which those hard-line TOS fans would never have allowed to be made (along with TNG and DS9).
And of course, someone's done the analysis with graphs and everything! Awesome! (though note the links to tumblr posts at the bottom that are now behind a sign-in wall ... fun).
The results aren't surprising to me, generally. I expected TNG to do worse, but also thought it did a pretty good job with female guest characters so it might score higher than I thought. DS9, I expected to do better than TNG, which, to my surprise is only marginally true. But I didn't expect, from memory, how much of that is attributable to so many characters breaking off into (hetero, yes even Odo) couples. Voyager obviously does very well. And Enterprise ... well we shouldn't expect much of that ... honestly, for me, this cements the show's status as a blight on this era to lean so masculine straight after voyager.
And of course TOS shows its age, which, surely by 1987, good Trek fans should have been aware of?
Beyond that, I can't help but think of SNW here, which, IMO has a wonderful cast/crew that's well balanced and which I'd expect to be doing well on the Bechdel (as low and superficial bar as it is). But, as it starts to transition into a TOS prequel/reboot (as it is trending from S2 and as the show runners are indicating), all of those TOS characters are going to carry that 60s baggage with them. They'll all be men (Uhura is already there!) and all be special miracle workers. La'an's story has already been sidelined into a Kirk romance. Pelia the engineer was already somewhat substituted by Scotty the engineer. As it goes on (presuming it does), I think it could begin to look awkward once you squint.
EDIT: For those asking about new seasons/series ... I found this page/blog by the author of the parent blog post ... which provides data for some new Trek (Disco and Picard S3 and SNW S1 it seems).
Somewhat notably to me (though only one data point) ... the one episode of SNW S1 that (clearly) fails the test is the one with Kirk in it.
In a similar vein though, while Disco generally does well (best of all Trek so far it seems), the author notes that Season two had the most episodes that were close to the line, because Michael’s arc was so intertwined with her search for her brother, Spock. That is, the more new Trek leans into TOS nostalgia, the worse this gets.
The Bechdel test doesn't tell you if something is 'good' or not, you mainly use it to identify trends in media overal. The fact that voyager predictably scored highest is, to me, a sign that it does measure something real, which I'd consider to be a hallmark of what a good metric is supposed to do.