Question

Age (x) (years)	Number Surviving (nx)	Proportion Surviving (lx)	log(nx)	Fecundity (fx)	lx fx	x lx fx
0	80,000	1.0		0	0	0
1	750	0.009375		0.1	0.0009375	0.0009375
2	400	0.005		2	0.01	0.02
3	320	0.004		80	0.32	0.96
4	240	0.003		120	0.36	1.44
5	80	0.001		160	0.16	0.8

calculate the lognx, and this is the answer from our professor:

Age (x) (years)	Number Surviving (nx)	Proportion Surviving (lx)	log(nx)	Fecundity (fx)
0	80,000	1.0	3.0	0
1	750	0.009	0.972	0.1
2	400	0.005	0.699	2
3	320	0.004	0.602	80
4	240	0.003	0.477	120
5	80	0.001	0.000	160

Why??? log (80,000)=4.903, why his answer is 3.0????

Answer 1

For age = 5 years,

Log (80) = 1.903

But it is written 0.000

Actually from all the log(nx) values, 1.903 is subtracted.

For example, for age = 0 years, log (80000) = 4.903

log 80000 - 1.903 = 3.0

Similar is the case for all the ages.

The professor has subtracted 1.903 from each answer. Normally, this is done because it is easy to compare the results with relative to each other. If we keep the original values, then it becomes difficult to compare them. We make one value as zero, and compare the rest with that value.