The definition
A training needs analysis, often shortened to TNA, is a structured comparison between the capability an organization needs and the capability it currently has, used to decide what training to provide. It is the step that should sit between measuring skills and spending a learning budget, and it is the step most often skipped.
Conventionally it runs at three levels. Organizational: what capabilities the strategy requires. Role: what each role needs to perform it. Individual: where each person stands against their role. The levels are ordered for a reason — individual needs are only meaningful once the role requirements exist to compare them with.
The survey trap
The quickest way to run a TNA is to ask people what training they want. It produces a fast, well-received answer that correlates with curiosity, recent frustration and whatever course a colleague mentioned — and only loosely with what the organization needs.
Preference data is worth collecting, because someone who wants to learn something will learn it faster. It is just not a needs analysis. The order matters: establish what the work requires, then use preference to decide who to invest in first among the people who need the same thing.
What the output should look like
A finished TNA names specific capabilities, the roles that need them, the number of people below the required level, and a recommendation for each — train, hire, reassign or accept. A document that describes the situation without recommending anything has not finished.
It should also say what is not being funded. A list of everything that would be nice is not a decision, and the credibility of the next analysis depends on this one having declined something visibly.