. Author manuscript; available in PMC: 2009 Apr 30.

Published in final edited form as: Mech Ageing Dev. 2007 Nov 4;128(11-12):706–716. doi: 10.1016/j.mad.2007.10.013

Table 1. Fitted Gompertz model and maximum likelihood estimates (MLE) values for intercept and slope.

Overall mortality data of individual genotypes as obtained by maximum likelihood estimates were best described with Gompertz parameters using WinModest v1.0.2 (Pletcher, 1999) (n= sample size, a= initial mortality rate, b= rate of demographic aging). Symbols *, †, indicates genetic background. Similar superscript in column for Gompertz parameters indicates no significant difference between populations. In column for Gompertz parameter ‘a’ significant difference is at p<0.01; in column for parameter ‘b’ significant difference is at p<0.001. A sensitivity analysis by varying the start parameters for ‘a’ and ‘b’ shows that the MLE parameters for each genotype is robust. The percent errors between the fitted and the actual mean life span for each genotype are small. The differences in mean lifespan were significantly different between KG06854R and Sod2ⁿ²⁸³^/+ (P<0.0001), between KG06854R and Sod2^wk/wk (P<0.0001), and between KG06854R and Sod2ⁿ²⁸³^/wk (P<0.0001), but not between Sod2ⁿ²⁸³^/+ and Sod2^wk/wk (P=0.1958).

	Gompertz Parameters				Max LS (days)	Actual Mean LS (days)	Fitted Mean LS (days)	% Error between Actual & Fitted Mean LS
	a (intercept)		b (slope)
	MLE value	Start Range	MLE value	Start Range
KG06854^R * (n=679)	0.00259 ^p	0.0001 − 0.003	0.05115 ^p	0.01 − 0.3	86	50.37850	50.51922	0.279
Sod2ⁿ²⁸³^/+ * (n=1038)	0.00288 ^p	0.0001 − 0.004	0.06522 ^q	0.01 − 0.4	69	41.49615	41.44730	0.118
Sod2^wk/wk * (n=704)	0.00250 ^p	0.0001 − 0.002	0.07501 ^r	0.01 − 0.2	65	39.63921	39.40065	0.602
Sod2^wk/n283 * (n=687)	0.00239 ^p	0.0001 − 0.003	0.10728 ^s	0.01 − 0.3	49	31.12664	30.97952	0.473
Sod2^+/+;{Sod2^+/+}^† (n=227)	0.00395 ^q	0.0001 − 0.002	0.04072 ^u	0.01 − 0.2	91	50.44934	50.06139	0.769