Sources
The evidence, in full
Every figure quoted on this site is below, with its source, its sample, its date, and a link to the original. Where a figure comes from a company that sells the thing its research supports, it says so. Where a number is old, or was asked in a particular way, it says that too.
If a claim cannot stand this kind of scrutiny, it does not belong on the site.
Gartner, 2024
Leader and manager development was HR leaders’ top priority for 2025, the third year running. Of the 805 asked about their managers, three-quarters said their managers are overwhelmed by the growth of the job, and 69 per cent said their leaders and managers are not equipped to lead change. Gartner also reported that 75 per cent of organisations had significantly updated their leadership development programmes and more than half had raised spend, and concluded they are not seeing results.
“Not seeing results” is Gartner’s own characterisation, not a survey figure. Gartner press releases summarise proprietary research, and the survey instrument is not public.
McKinsey, 2017
Only 11 per cent of more than 500 executives McKinsey polled worldwide strongly agreed that their leadership development achieves and sustains the desired results.
Nine years old. McKinsey does not publish the fieldwork dates or a country breakdown for this poll.
Harvard Business Review, 2016
Companies spent 160 billion dollars in the United States and close to 356 billion dollars globally on training and education in 2015. Harvard Business Review calls it the great training robbery, because the learning does not lead to better performance: people soon revert to their old ways.
The 356 billion dollar figure is global spend for 2015, and Harvard Business Review gives no source for it. Treat it as a figure they assert rather than one they measured, and note it is a decade old.
Read the HBR article Subscription may be required
DDI, 2025
71 per cent of leaders report increased stress since taking the role, and 40 per cent have considered leaving leadership altogether to protect their wellbeing.
Vendor research. DDI sells leadership assessment and development, so its findings support its product. It is quoted here as DDI’s own research, not as independent.
Read the DDI forecast The figures are inside the downloadable report
Gallup, 2015 (engagement variance)
Managers account for at least 70 per cent of the variance in employee engagement across business units.
Vendor research, and eleven years old. Gallup’s own wording is “at least 70 per cent”, and the variance is between business units, not within any one person’s engagement. Gallup names the underlying database but does not publish how the figure is derived.
Zenger Folkman, 2015
A study of 360-degree feedback on roughly 69,000 managers, rated by around 750,000 people, found that leaders’ views of themselves routinely failed to match how others saw them, and that the weakest leaders overrated themselves the most.
Ten years old. The study’s own headline finding is the reverse emphasis: leaders who underrate themselves tend to be rated more highly by the people around them.
Read the HBR article Subscription may be required
Chartered Management Institute, 2023
27 per cent of workers describe their manager as highly effective. 82 per cent of people entering management have had no formal management or leadership training, which the UK calls accidental managers.
CMI is the UK chartered professional body for managers, not a commercial vendor.
Gallup, 2015 (leaving to escape a manager)
One in two employees have left a job at some point in their career to get away from their manager.
Eleven years old and US only. Not to be confused with the separate CMI finding that half of workers under an ineffective manager plan to leave within a year.
PwC, 2021
77 per cent of senior management feel a personal connection to their company’s purpose, against 54 per cent for the rest of the workforce.
Five years old, and there is no later edition of the survey.
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Tell me, and I will fix it. A claim that cannot be sourced does not belong here.