Table 2. Parameters needed for log rank test calculations obtained in an example data set of myelofibrosis patients.

N	Time (months)	Status	Group	I	O	R	RGr1	RGr2	EGr1	EGr2	VMantel*	O/R	Λ†	W‡	W2
1	0.10	0	1	1	0	67	41	26					0.00	0.00	0.00
2	0.57	1	1	2	1	66	40	26	0.61	0.39	0.24	0.02	0.02	0.98	0.97
3	0.60	1	2	3	1	65	39	26	0.60	0.40	0.24	0.02	0.03	0.97	0.94
4	1.17	1	1	4	1	64	39	25	0.61	0.39	0.24	0.02	0.05	0.95	0.91
5	1.47	1	1	5	1	63	38	25	0.60	0.40	0.24	0.02	0.06	0.94	0.88
6	1.57	1	2	6	1	62	37	25	0.60	0.40	0.24	0.02	0.08	0.92	0.85
7	1.70	1	2	7	1	61	37	24	0.61	0.39	0.24	0.02	0.09	0.91	0.82
8	2.17	0	1	7	1	61	37	24					0.09	0.09	0.01
9	2.23	0	2	7	1	61	37	24					0.09	0.09	0.01
10	4.90	1	2	8	1	58	36	22	0.62	0.38	0.24	0.02	0.11	0.89	0.79
The first ten observations are shown. For specific calculations please see Table 1 and the supplementary file. N – number of observation. Time - duration of follow-up, recorded in months in our example. Status - censoring variable, 1 for death and 0 for alive or lost to follow-up. Group - 1 for grade < 3 myelofibrosis and 2 for grade 3 myelofibrosis patients. I – number of interval. O – observed number of deaths per interval. R – overall number at risk per interval. RGr1 and RGr2 – overall number at risk in a specific group per interval. EGr1 and EGr2 – expected number of deaths in a specific group per interval. * Variance of the log-rank test calculated by Mantel method. †Λ – the Nelson-Aalen estimator. ‡W – score for the Peto log-rank test.