In Sion, does a precise figure make a proposal more persuasive?
In a commercial or budget proposal, how an amount is presented is not neutral. The managerial question is specific: should additional digits be used to strengthen a proposal, or might they suggest knowledge that the author does not possess?
What the literature establishes
Chris Janiszewski and Dan Uy (2008, Psychological Science) show experimentally that the precision of a numerical anchor influences subsequent adjustment. Participants move less far from a precise anchor than from a rounded one. The proposed mechanism concerns the granularity of the mental scale used: a precise number encourages smaller adjustments.
Precision as a signal of knowledge
Malia F. Mason, Alice J. Lee, Elizabeth A. Wiley and Daniel R. Ames (2013, Journal of Experimental Social Psychology) examine this phenomenon in negotiations. Their experiments show that precise opening offers can elicit counteroffers closer to the initial demand. They also indicate that precision can lead recipients to attribute greater knowledge to the person making the offer.
The premature conclusion
One might conclude that rounded amounts should simply be replaced with more detailed figures. Yet these studies demonstrate an effect on judgement and negotiation, not an improvement in the underlying calculation. A proposal can therefore become more influential without becoming more accurate: displayed precision is not evidence. (our executive and employee training programmes)
What these findings cannot promise
These experiments do not demonstrate that greater precision produces lasting improvements in trust, decision quality or contract delivery. Nor do they justify directly generalising the findings to estimates concerning healthcare, hydropower generation or visitor numbers. Common practice remains problematic when a detailed amount circulates without its assumptions: readers may attribute a robustness to it that the document does not allow them to verify.
A practical check in Sion
Within SHR's Communication programme, an exercise applicable in Sion is to review a team's numerical proposals over two weeks, whether they concern hydropower maintenance, healthcare organisation, a wine-sector service or an Alpine tourism offer. For each amount, record whether the document distinguishes a fixed price, a documented calculation and an estimate subject to uncertainty, then check whether the level of precision is supported by an accessible basis. The main measure is the proportion of amounts presented as calculated for which a colleague can locate the underlying information and reproduce the calculation. A second reader separately flags estimates presented as certainties: the exercise checks the traceability of the message, without claiming to measure its persuasive power on its own. To go further: explore the Communication training in Sion in the canton of Valais, or browse our executive and employee training programmes in Switzerland.
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