The total that concealed a choice

An original exposition about an invented programme report.

At the end of a trial season, a workshop centre reported on three new sessions. The opening sentence announced: “Thirty-five of the forty-two people who attended completed an item.” Every number was correct, and the sentence seemed to offer a neat verdict on the whole programme.

The total folds three different stories into one. It leaves out the twelve empty places, because only people who attended are counted. It also smooths away the differences between the sessions. Once the rows are separated, the programme’s single, confident result begins to fracture.

Whether this matters depends on the decision being made. Someone allocating rooms needs to know how many people arrived for each session. An organiser deciding which sessions to repeat needs to compare their separate outcomes. A future visitor might ask what “completed” means and whether an unfinished item could still represent a worthwhile session. The same total cannot answer all three questions.

The arithmetic has not lied; the sentence has simply answered an easier question. Yet printing every available detail would not automatically make the report clearer. A page crowded with minor figures could bury the important differences as effectively as the single total did. Selection is still necessary, but the purpose of the report should govern what is selected.

A useful summary must therefore be shorter than its evidence without becoming smaller than its responsibility. It should state what has been counted, preserve any difference that could alter a decision and acknowledge what the figures cannot show.

How does the writer use the figures and the different decisions people might make to explain why an accurate summary can still be misleading?