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Article | EX Insights

Survey best practice: Tips for creating a historical perspective


By Adam Zuckerman | January 13, 2020

How to set up your survey to create trends.

When it comes to employee survey methodology, one of the topics we’re frequently asked about is historical trending. Here are three things we’ve learned about creating historical perspectives from working with various clients over many decades:

  1. 01


    There is no perfect interval between surveys. In general, given the pace of business today, we recommend surveying at least on an annual basis. It’s difficult to imagine that a historical benchmark greater than a year old could provide real insight. This doesn’t mean there isn’t value in seeing multiple years strung together. However, to appreciate the overall arc of change and to gain helpful insight, the most immediate historical comparison should not be greater than 12 months.

    A related point concerns the ideal amount of time to wait between surveys, such as regular pulse surveys or follow-ups from a large-scale census. Again, there is no perfect answer that fits all cases. Timing depends on the focus of the survey. Higher-level issues that change slowly, like company strategy, should be asked less frequently than local issues that change more often like workload and teamwork. In general, we find a two- to three-month interval between surveys strike the right balance between delivering timely insights, providing enough time for meaningful change to occur, and avoiding survey fatigue.

  2. 02


    As with everything else in life, organizational structures change over time. This is why accurate historical tracking requires a mapping process, at least for the most common “group-to-group” historical tracking (see #3 below). This process can be time-consuming when there is significant organizational change. At Willis Towers Watson, we are constantly developing new software features to make this process less burdensome.

    When advising clients, we emphasize a “50% rule.” This means you should have at least 50% overlap between two groups before considering them sufficiently matched for historical comparison. Of course, this is only a rule of thumb. Even with this relatively low bar, most companies find themselves with many groups that have no historical match. Unfortunate, perhaps; but in our experience, it’s better to show no trend at all, than to show a misleading one.

  3. 03

    Group vs. individual level

    One of the ways to mitigate the burden of mapping, is to base comparisons at the individual versus group level. In group-to-group comparisons, which is the Willis Towers Watson Employee Engagement Software default, a current year group is compared to the same group from the prior year, even though it’s likely some new employees have joined and others have left. In this case, the group is the focus.

    In individual level comparisons, a current year group is compared with the aggregated historical scores of individuals that are currently in the group, and not with the same group from the prior year. This means no group-to-group mapping is required, and if enough employees took the survey last time, some historical benchmark will exist. In addition, historical scores from the prior year will be recalculated to reflect the current makeup of that team or department. This can be disorienting to managers, but this method of historical trending in our Advanced Analytics module can facilitate easier on-the-fly, long-term trending for any potential group configuration.

    We hope these tips on historical mapping have been helpful. To learn more, log in to Willis Towers Watson Employee Engagement Software today or contact us for a demo.


Product Leader
Willis Towers Watson Employee Engagement Software

Adam is responsible for the overall development and direction of Willis Towers Watson Employee Engagement Software. His goal is to create the world’s greatest software for delivering insight and enabling actions that enhance employee experience, company culture, and business performance. Outside of work, Adam enjoys off-roading in his Jeep and spending time with his family. Follow Adam on Twitter.

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