Table 1.

Statistical analysis of lifespan data for WT, CuZnSOD, catalase (CAT), CuZnSOD/CAT, and CuZnSOD/MnSOD transgenic mice

	WT	CuZnSOD-Tg	CAT-Tg	CuZnSOD/CAT-Tg	CuZnSOD/MnSOD-Tg
Number	44	44	44	47	54
Mean (days)	922	915	916	922.3	899
Median (days)	941	944	949	945	914
90% survival (days)	1090	1131	1099	1098	1075
Maximum (days)	1231	1229	1139	1163	1144

The survival data from Fig. 1 are expressed in days. Mean survivals (± standard error of the mean) for each group were compared to the WT group by performing a Student's t-test upon log-transformed survival times from the respective groups. The median and 90th percentile survivals for each group were compared to the WT group using a score test adapted from Wang et al. (2004). All the above comparisons were made individually between each experimental group (CuZnSOD-Tg, CAT-Tg, CuZnSOD/CAT-Tg, and CuZnSOD/MnSOD-Tg) and the WT control group; and Holm's method (Holm, 1979) was used to correct for multiple comparisons. None of the comparisons were significant, with p-values ranging from 0.19 to 0.97. After correcting for multiple comparisons, the p-values all became 1.