Table 2 Programme- and gender-specific pair-wise within-person standard deviations s̄_p and s̄_r, the corresponding absolute LLD_a and relative LLD_r limits, and the 95th percentiles for observed year-to-year ΔFEV₁ and %ΔFEV₁

Programme	Gender	n†	Mean interval (months)	Absolute limit			Relative limit
Programme	Gender	n†	Mean interval (months)	s̄_p (ml)	LLD_a (ml/y)	95th percentile ΔFEV₁	s̄_r (%)	LLD_r (%)	95th percentile %ΔFEV₁
P1 (1990–6)	Male	281	10.5	114.6	297	310	2.9	7.4	7.6
P1 (1990–6)	Female	63	10.4	74.6	204	190	2.5	6.6	7.5
P2 (1988–98)	Male	1930	12.2	174.0	435	440	5.1	12.6	12.2
P2 (1988–98)	Female	225	12.1	137.2	349	346	5.1	12.5	12.9
P3A (1990–9)	Male	4304	11.9	161.7	406	380	4.2	10.6	9.9
P3A (1990–9)	Female	147	11.6	133.0	339	320	4.1	10.2	9.2
P3B (2000–4)	Male	3062	11.5	246.9	604	560	6.3	15.3	13.8
P3B (2000–4)	Female	127	11.3	222.2	547	490	6.5	15.8	14.3
P4	Male	15872	12.0	149.5	378	370	5.7	14.2	14.3
P4	Female	9570	12.0	109.3	284	280	6.0	15.0	15.8

†Number of year-to-year intervals on which statistics are based.