Employee Surveys should not be about 'the number'
In reality, the figure is flawed. Why? As far as senior leaders are concerned, it's turkeys voting for Christmas - they're scoring themselves, so they're bound to give high scores. And some may put pressure on their teams to score favourably. Employees with an axe to grind will also give artificially low scores.
Now, this is not to say that the number is useless - it does give a benchmark, as the above will be the case for all surveys. But it could be argued that the number does more harm than good.
Why? Those departments who score highly are likely to believe that all's well in the garden and they can carry on as they were - i.e. not bother to react to any feedback. (But as outlined - is their number 'real'?) Those with a low score are likely to find excuses for this, and may resist any changes. (And their 'real' score could actually be higher.) Embedding change can take time and can be painful, so those who have reacted to feedback from previous surveys may suffer a short-term blip - and any reduction in the score is seen as going backwards. (But sometimes you have to go backwards to come forwards.)
So, what's the alternative? A suggestion is to not publish 'the number'. Instead, publish the actions per department coming from the feedback and transparently track progress. This way, no blame or shame is attached – all departments will be focussed on using the feedback that their own people have given to drive improvements. And if employees see that their feedback is taken seriously and they're involved in improvement plans, then this should, in itself, increase engagement/satisfaction.
These actions will differ in timescales, so the temptation to turn these into KPIs should be resisted, as the improvements could be rushed. (And ditto KPIs for the survey numbers, they end up being all about achieving ‘the number’.)
But if you don't publish 'the number' then how do you assess progress? Easy, just look at your people metrics such as mojo scores, sickness, turnover etc. (In reality, there could still be ‘the number’ but it could be for limited eyes only, such as the Head of Employee Experience.)
Employee Voice mechanisms, such as surveys, are put in place to affect improvements – and having a continuous improvement culture is far more important than an infrequent, flawed number.