Table 1.

A summary of age and time of employment in each analyzed cluster in oil rig workers in Poland, surveyed in 1993–2014 on oil rigs

	1. Stress resisting group (N = 49)		2. Stress sensitizing group (N = 66)		3. Flexible group (N = 52)
	M±SD	min.–max	M±SD	min.–max	M±SD	min.–max
Age [years]
1993–1998 – start of research	28.3±7.3	27–45	31.2±6.8	26–47	27.6±8.6	24–47
2010–2014 – end of research	42.5±7.3	46–59	49.9±6.8	34–65	44.8±8.6	41–64
Time of employment [years]	14.2±7.3	11–31	18.7±6.8	13–34	17.2±8.6	13–37