I'm always amused by well-paid journalists and pundits complaining that teacher's compensation isn't closely enough linked to performance. Is Megan hauled into James Bennet's office once a week, presented with updated traffic numbers where traffic boosts and drops are disaggregated from intra-Atlantic links and general noise, and then paid less or more depending on her performance? Of course not. Andrew Sullivan doesn't even trust his traffic numbers. Are pundits, once a year, asked in for a sit-down with their editors, during which they are presented with a comprehensive list of their predictions and opinions, and then offered a bonus based on accuracy? Does The Atlantic pick through reader mail and commission surveys to evaluate how much interest is generated by Clive Crook's work, and then reconsider his contract based off those metrics? Of course not.
Indeed, not only are these practices not in place, but journalists would sob and shriek and scream were they ever to be implemented. Our work isn't supposed to generate traffic, it's here to inform; our work isn't merely to inform, it's here to provoke and spark interest; our work isn't merely here to provoke and spark interest, it's here to add to the paper's reputation and cover important topics; blah blah blah. There's no merit pay in journalism, and no agreed upon metrics measuring quality. There's no way to track improvement, and no agreement on what improvement would mean, or how to disentangle individual effort from luck, chance, personal relationships, and so forth. But no end of journalists are happy, when talking about teachers, to demand merit pay, and performance tracking, and all other sorts of incentives they're neither exposed to nor would support.
By the way: I support merit pay (and for journalists too: How much the better if we could boost our salaries by doing graduate work in our subjects!), but if you've never thought through the difficulties of implementing such a program, you might want to read through these comments.