"mistaken decision" is a correct and usable phrase in written English.
It is used to describe a decision that has later been revealed to be wrong or misguided. Example: The government was accused of making a mistaken decision when they chose to ignore scientific advice.
The networks' mistaken decision to call Florida so quickly came under fire from officials of the Bush campaign and some who analyze the news media.
Conversely, computerised bees that blindly followed the waggle dances of others without first checking whether the site was, in fact, as advertised, led to a swift but mistaken decision.
One City Council member said that at least part of the problem rose from what he called a mistaken decision to place the command center next to a terrorist target.
In a statement, ITT said it was "deeply disappointed" with the SEC's "mistaken" decision to bring the case.
Cue the BBC's mistaken decision to give Griffin a platform on Question Time tonight.
Three unforced errors and a mistaken decision to allow a Wozniacki lob to land inside the line cost King still another game.
Rankine's poem refers to the mistaken decisions by umpire Mariana Alves at the US Open in 2004, which contributed to your early exit from the tournament.
The disastrous position in which this country now finds itself is the direct consequence of two fundamentally mistaken decisions that were May's responsibility alone.
Secondly, the individual social worker involved was severely censured for her lack of knowledge and what was seen as a series of mistaken decisions.
The point is that mistaken decisions to go to war have a more terrible cost than almost any other sort of mistake, and to remember the price that the people of Iraq have paid.
And it showed that there is a golden opportunity for liberals in both countries to tackle the public concerns that motivated the mistaken decisions to vote for Brexit and Donald Trump.
